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Sample records for catalysts substantially enhanced

  1. Substantial bulk photovoltaic effect enhancement via nanolayering.

    PubMed

    Wang, Fenggong; Young, Steve M; Zheng, Fan; Grinberg, Ilya; Rappe, Andrew M

    2016-01-21

    Spontaneous polarization and inversion symmetry breaking in ferroelectric materials lead to their use as photovoltaic devices. However, further advancement of their applications are hindered by the paucity of ways of reducing bandgaps and enhancing photocurrent. By unravelling the correlation between ferroelectric materials' responses to solar irradiation and their local structure and electric polarization landscapes, here we show from first principles that substantial bulk photovoltaic effect enhancement can be achieved by nanolayering PbTiO3 with nickel ions and oxygen vacancies ((PbNiO2)x(PbTiO3)(1-x)). The enhancement of the total photocurrent for different spacings between the Ni-containing layers can be as high as 43 times due to a smaller bandgap and photocurrent direction alignment for all absorption energies. This is due to the electrostatic effect that arises from nanolayering. This opens up the possibility for control of the bulk photovoltaic effect in ferroelectric materials by nanoscale engineering of their structure and composition.

  2. Substantial bulk photovoltaic effect enhancement via nanolayering

    SciTech Connect

    Wang, Fenggong; Young, Steve M.; Zheng, Fan; Grinberg, Ilya; Rappe, Andrew M.

    2016-01-21

    Spontaneous polarization and inversion symmetry breaking in ferroelectric materials lead to their use as photovoltaic devices. However, further advancement of their applications are hindered by the paucity of ways of reducing bandgaps and enhancing photocurrent. By unravelling the correlation between ferroelectric materials’ responses to solar irradiation and their local structure and electric polarization landscapes, here we show from first principles that substantial bulk photovoltaic effect enhancement can be achieved by nanolayering PbTiO3 with nickel ions and oxygen vacancies ((PbNiO2)x(PbTiO3)1–x). The enhancement of the total photocurrent for different spacings between the Ni-containing layers can be as high as 43 times due to a smaller bandgap and photocurrent direction alignment for all absorption energies. This is due to the electrostatic effect that arises from nanolayering. Lastly, this opens up the possibility for control of the bulk photovoltaic effect in ferroelectric materials by nanoscale engineering of their structure and composition.

  3. Substantial bulk photovoltaic effect enhancement via nanolayering

    DOE PAGES

    Wang, Fenggong; Young, Steve M.; Zheng, Fan; ...

    2016-01-21

    Spontaneous polarization and inversion symmetry breaking in ferroelectric materials lead to their use as photovoltaic devices. However, further advancement of their applications are hindered by the paucity of ways of reducing bandgaps and enhancing photocurrent. By unravelling the correlation between ferroelectric materials’ responses to solar irradiation and their local structure and electric polarization landscapes, here we show from first principles that substantial bulk photovoltaic effect enhancement can be achieved by nanolayering PbTiO3 with nickel ions and oxygen vacancies ((PbNiO2)x(PbTiO3)1–x). The enhancement of the total photocurrent for different spacings between the Ni-containing layers can be as high as 43 times duemore » to a smaller bandgap and photocurrent direction alignment for all absorption energies. This is due to the electrostatic effect that arises from nanolayering. Lastly, this opens up the possibility for control of the bulk photovoltaic effect in ferroelectric materials by nanoscale engineering of their structure and composition.« less

  4. Substantial bulk photovoltaic effect enhancement via nanolayering

    PubMed Central

    Wang, Fenggong; Young, Steve M.; Zheng, Fan; Grinberg, Ilya; Rappe, Andrew M.

    2016-01-01

    Spontaneous polarization and inversion symmetry breaking in ferroelectric materials lead to their use as photovoltaic devices. However, further advancement of their applications are hindered by the paucity of ways of reducing bandgaps and enhancing photocurrent. By unravelling the correlation between ferroelectric materials' responses to solar irradiation and their local structure and electric polarization landscapes, here we show from first principles that substantial bulk photovoltaic effect enhancement can be achieved by nanolayering PbTiO3 with nickel ions and oxygen vacancies ((PbNiO2)x(PbTiO3)1−x). The enhancement of the total photocurrent for different spacings between the Ni-containing layers can be as high as 43 times due to a smaller bandgap and photocurrent direction alignment for all absorption energies. This is due to the electrostatic effect that arises from nanolayering. This opens up the possibility for control of the bulk photovoltaic effect in ferroelectric materials by nanoscale engineering of their structure and composition. PMID:26791545

  5. A substantial and unexpected enhancement of motion perception in autism.

    PubMed

    Foss-Feig, Jennifer H; Tadin, Duje; Schauder, Kimberly B; Cascio, Carissa J

    2013-05-08

    Atypical perceptual processing in autism spectrum disorder (ASD) is well documented. In addition, growing evidence supports the hypothesis that an excitatory/inhibitory neurochemical imbalance might underlie ASD. Here we investigated putative behavioral consequences of the excitatory/inhibitory imbalance in the context of visual motion perception. As stimulus size increases, typical observers exhibit marked impairments in perceiving motion of high-contrast stimuli. This result, termed "spatial suppression," is believed to reflect inhibitory motion-processing mechanisms. Motion processing is also affected by gain control, an inhibitory mechanism that underlies saturation of neural responses at high contrast. Motivated by these behavioral correlates of inhibitory function, we investigated motion perception in human children with ASD (n = 20) and typical development (n = 26). At high contrast, both groups exhibited similar impairments in motion perception with increasing stimulus size, revealing no apparent differences in spatial suppression. However, there was a substantial enhancement of motion perception in ASD: children with ASD exhibited a consistent twofold improvement in perceiving motion. Hypothesizing that this enhancement might indicate abnormal weakening of response gain control, we repeated our measurements at low contrast, where the effects of gain control should be negligible. At low contrast, we indeed found no group differences in motion discrimination thresholds. These low-contrast results, however, revealed weaker spatial suppression in ASD, suggesting the possibility that gain control abnormalities in ASD might have masked spatial suppression differences at high contrast. Overall, we report a pattern of motion perception abnormalities in ASD that includes substantial enhancements at high contrast and is consistent with an underlying excitatory/inhibitory imbalance.

  6. Oxidation catalyst

    DOEpatents

    Ceyer, Sylvia T.; Lahr, David L.

    2010-11-09

    The present invention generally relates to catalyst systems and methods for oxidation of carbon monoxide. The invention involves catalyst compositions which may be advantageously altered by, for example, modification of the catalyst surface to enhance catalyst performance. Catalyst systems of the present invention may be capable of performing the oxidation of carbon monoxide at relatively lower temperatures (e.g., 200 K and below) and at relatively higher reaction rates than known catalysts. Additionally, catalyst systems disclosed herein may be substantially lower in cost than current commercial catalysts. Such catalyst systems may be useful in, for example, catalytic converters, fuel cells, sensors, and the like.

  7. Enhanced catalyst for conversion of syngas to liquid motor fuels

    DOEpatents

    Coughlin, P.K.; Rabo, J.A.

    1985-12-03

    Synthesis gas comprising carbon monoxide and hydrogen is converted to C[sub 5][sup +] hydrocarbons suitable for use as liquid motor fuels by contact with a dual catalyst system capable of enhancing the selectivity of said conversion to motor fuel range hydrocarbons and the quality of the resulting motor fuel product. The catalyst composition employs a Fischer-Tropsch catalyst, together with a co-catalyst/support component comprising a SAPO silicoaluminophosphate, non-zeolitic molecular sieve catalyst.

  8. Enhanced catalyst for conversion of syngas to liquid motor fuels

    DOEpatents

    Coughlin, Peter K.; Rabo, Jule A.

    1985-01-01

    Synthesis gas comprising carbon monoxide and hydrogen is converted to C.sub.5.sup.+ hydrocarbons suitable for use as liquid motor fuels by contact with a dual catalyst system capable of enhancing the selectivity of said conversion to motor fuel range hydrocarbons and the quality of the resulting motor fuel product. The catalyst composition employs a Fischer-Tropsch catalyst, together with a co-catalyst/support component comprising SAPO silicoaluminophosphate, non-zeolitic molecular sieve catalyst.

  9. Dispersion enhanced metal/zeolite catalysts

    DOEpatents

    Sachtler, W.M.H.; Tzou, M.S.; Jiang, H.J.

    1987-03-31

    Dispersion stabilized zeolite supported metal catalysts are provided as bimetallic catalyst combinations. The catalyst metal is in a reduced zero valent form while the dispersion stabilizer metal is in an unreduced ionic form. Representative catalysts are prepared from platinum or nickel as the catalyst metal and iron or chromium dispersion stabilizer.

  10. Dispersion enhanced metal/zeolite catalysts

    DOEpatents

    Sachtler, Wolfgang M. H.; Tzou, Ming-Shin; Jiang, Hui-Jong

    1987-01-01

    Dispersion stabilized zeolite supported metal catalysts are provided as bimetallic catalyst combinations. The catalyst metal is in a reduced zero valent form while the dispersion stabilizer metal is in an unreduced ionic form. Representative catalysts are prepared from platinum or nickel as the catalyst metal and iron or chromium dispersion stabilizer.

  11. Palladium–platinum core-shell icosahedra with substantially enhanced activity and durability towards oxygen reduction

    SciTech Connect

    Wang, Xue; Choi, Sang-Il; Roling, Luke T.; Luo, Ming; Ma, Cheng; Zhang, Lei; Chi, Miaofang; Liu, Jingyue; Xie, Zhaoxiong; Herron, Jeffrey A.; Mavrikakis, Manos; Xia, Younan

    2015-07-02

    Conformal deposition of platinum as ultrathin shells on facet-controlled palladium nanocrystals offers a great opportunity to enhance the catalytic performance while reducing its loading. Here we report such a system based on palladium icosahedra. Owing to lateral confinement imposed by twin boundaries and thus vertical relaxation only, the platinum overlayers evolve into a corrugated structure under compressive strain. For the core-shell nanocrystals with an average of 2.7 platinum overlayers, their specific and platinum mass activities towards oxygen reduction are enhanced by eight- and sevenfold, respectively, relative to a commercial catalyst. Density functional theory calculations indicate that the enhancement can be attributed to the weakened binding of hydroxyl to the compressed platinum surface supported on palladium. After 10,000 testing cycles, the mass activity of the core-shell nanocrystals is still four times higher than the commercial catalyst. Ultimately, these results demonstrate an effective approach to the development of electrocatalysts with greatly enhanced activity and durability.

  12. Palladium-platinum core-shell icosahedra with substantially enhanced activity and durability towards oxygen reduction.

    PubMed

    Wang, Xue; Choi, Sang-Il; Roling, Luke T; Luo, Ming; Ma, Cheng; Zhang, Lei; Chi, Miaofang; Liu, Jingyue; Xie, Zhaoxiong; Herron, Jeffrey A; Mavrikakis, Manos; Xia, Younan

    2015-07-02

    Conformal deposition of platinum as ultrathin shells on facet-controlled palladium nanocrystals offers a great opportunity to enhance the catalytic performance while reducing its loading. Here we report such a system based on palladium icosahedra. Owing to lateral confinement imposed by twin boundaries and thus vertical relaxation only, the platinum overlayers evolve into a corrugated structure under compressive strain. For the core-shell nanocrystals with an average of 2.7 platinum overlayers, their specific and platinum mass activities towards oxygen reduction are enhanced by eight- and sevenfold, respectively, relative to a commercial catalyst. Density functional theory calculations indicate that the enhancement can be attributed to the weakened binding of hydroxyl to the compressed platinum surface supported on palladium. After 10,000 testing cycles, the mass activity of the core-shell nanocrystals is still four times higher than the commercial catalyst. These results demonstrate an effective approach to the development of electrocatalysts with greatly enhanced activity and durability.

  13. Enhanced catalyst stability for cyclic co methanation operations

    DOEpatents

    Risch, Alan P.; Rabo, Jule A.

    1983-01-01

    Carbon monoxide-containing gas streams are passed over a catalyst to deposit a surface layer of active surface carbon thereon essentially without the formation of inactive coke. The active carbon is thereafter reacted with steam or hydrogen to form methane. Enhanced catalyst stability for long term, cyclic operation is obtained by the incorporation of an alkali or alkaline earth dopant in a silica binding agent added to the catalyst-support additive composition.

  14. Enhanced catalyst for converting synthesis gas to liquid motor fuels

    DOEpatents

    Coughlin, Peter K.

    1986-01-01

    The conversion of synthesis gas to liquid molar fuels by means of a cobalt Fischer-Tropsch catalyst composition is enhanced by the addition of molybdenum, tungsten or a combination thereof as an additional component of said composition. The presence of the additive component increases the olefinic content of the hydrocarbon products produced. The catalyst composition can advantageously include a support component, such as a molecular sieve, co-catalyst/support component or a combination of such support components.

  15. Palladium–platinum core-shell icosahedra with substantially enhanced activity and durability towards oxygen reduction

    PubMed Central

    Wang, Xue; Choi, Sang-Il; Roling, Luke T.; Luo, Ming; Ma, Cheng; Zhang, Lei; Chi, Miaofang; Liu, Jingyue; Xie, Zhaoxiong; Herron, Jeffrey A.; Mavrikakis, Manos; Xia, Younan

    2015-01-01

    Conformal deposition of platinum as ultrathin shells on facet-controlled palladium nanocrystals offers a great opportunity to enhance the catalytic performance while reducing its loading. Here we report such a system based on palladium icosahedra. Owing to lateral confinement imposed by twin boundaries and thus vertical relaxation only, the platinum overlayers evolve into a corrugated structure under compressive strain. For the core-shell nanocrystals with an average of 2.7 platinum overlayers, their specific and platinum mass activities towards oxygen reduction are enhanced by eight- and sevenfold, respectively, relative to a commercial catalyst. Density functional theory calculations indicate that the enhancement can be attributed to the weakened binding of hydroxyl to the compressed platinum surface supported on palladium. After 10,000 testing cycles, the mass activity of the core-shell nanocrystals is still four times higher than the commercial catalyst. These results demonstrate an effective approach to the development of electrocatalysts with greatly enhanced activity and durability. PMID:26133469

  16. Palladium–platinum core-shell icosahedra with substantially enhanced activity and durability towards oxygen reduction

    DOE PAGES

    Wang, Xue; Choi, Sang-Il; Roling, Luke T.; ...

    2015-07-02

    Conformal deposition of platinum as ultrathin shells on facet-controlled palladium nanocrystals offers a great opportunity to enhance the catalytic performance while reducing its loading. Here we report such a system based on palladium icosahedra. Owing to lateral confinement imposed by twin boundaries and thus vertical relaxation only, the platinum overlayers evolve into a corrugated structure under compressive strain. For the core-shell nanocrystals with an average of 2.7 platinum overlayers, their specific and platinum mass activities towards oxygen reduction are enhanced by eight- and sevenfold, respectively, relative to a commercial catalyst. Density functional theory calculations indicate that the enhancement can bemore » attributed to the weakened binding of hydroxyl to the compressed platinum surface supported on palladium. After 10,000 testing cycles, the mass activity of the core-shell nanocrystals is still four times higher than the commercial catalyst. Ultimately, these results demonstrate an effective approach to the development of electrocatalysts with greatly enhanced activity and durability.« less

  17. Enhanced Oxidation Catalysts for Water Reclamation

    NASA Technical Reports Server (NTRS)

    Jolly, Clifford D.

    1999-01-01

    This effort seeks to develop and test high-performance, long operating life, physically stable catalysts for use in spacecraft water reclamation systems. The primary goals are to a) reduce the quantity of expendable water filters used to purify water aboard spacecraft, b) to extend the life of the oxidation catalysts used for eliminating organic contaminants in the water reclamation systems, and c) reduce the weight/volume of the catalytic oxidation systems (e.g. VRA) used. This effort is targeted toward later space station utilization and will consist of developing flight-qualifiable catalysts and long-term ground tests of the catalyst prior to their utilization in flight. Fixed -bed catalytic reactors containing 5% platinum on granular activated carbon have been subjected to long-term dynamic column tests to measure catalyst stability vs throughput. The data generated so far indicate that an order of magnitude improvement can be obtained with the treated catalysts vs the control catalyst, at only a minor loss (approx 10%) in the initial catalytic activity.

  18. Nanoscale Catalysts for NMR Signal Enhancement by Reversible Exchange

    PubMed Central

    2015-01-01

    Two types of nanoscale catalysts were created to explore NMR signal enhancement via reversible exchange (SABRE) at the interface between heterogeneous and homogeneous conditions. Nanoparticle and polymer comb variants were synthesized by covalently tethering Ir-based organometallic catalysts to support materials composed of TiO2/PMAA (poly(methacrylic acid)) and PVP (polyvinylpyridine), respectively, and characterized by AAS, NMR, and DLS. Following parahydrogen (pH2) gas delivery to mixtures containing one type of “nano-SABRE” catalyst particle, a target substrate, and ethanol, up to ∼(−)40-fold and ∼(−)7-fold 1H NMR signal enhancements were observed for pyridine substrates using the nanoparticle and polymer comb catalysts, respectively, following transfer to high field (9.4 T). These enhancements appear to result from intact particles and not from any catalyst molecules leaching from their supports; unlike the case with homogeneous SABRE catalysts, high-field (in situ) SABRE effects were generally not observed with the nanoscale catalysts. The potential for separation and reuse of such catalyst particles is also demonstrated. Taken together, these results support the potential utility of rational design at molecular, mesoscopic, and macroscopic/engineering levels for improving SABRE and HET-SABRE (heterogeneous-SABRE) for applications varying from fundamental studies of catalysis to biomedical imaging. PMID:26185545

  19. Catalyst Additives to Enhance Mercury Oxidation and Capture

    SciTech Connect

    Thomas K. Gale

    2006-06-30

    Catalysis is the key fundamental ingredient to convert elemental mercury in coal-fired power stations into its oxidized forms that are more easily captured by sorbents, ESPs, baghouses, and wet scrubbers, whether the catalyst be unburned carbon (UBC) in the ash or vanadium pentoxide in SCR catalysts. This project has investigated several different types of catalysts that enhance mercury oxidation in several different ways. The stated objective of this project in the Statement of Objectives included testing duct-injection catalysts, catalyst-sorbent hybrids, and coated low-pressure-drop screens. Several different types of catalysts were considered for duct injection, including different forms of iron and carbon. Duct-injection catalysts would have to be inexpensive catalysts, as they would not be recycled. Iron and calcium had been shown to catalyze mercury oxidation in published bench-scale tests. However, as determined from results of an on-going EPRI/EPA project at Southern Research, while iron and calcium did catalyze mercury oxidation, the activity of these catalysts was orders of magnitude below that of carbon and had little impact in the short residence times available for duct-injected catalysts or catalyst-sorbent hybrids. In fact, the only catalyst found to be effective enough for duct injection was carbon, which is also used to capture mercury and remove it from the flue gas. It was discovered that carbon itself is an effective catalyst-sorbent hybrid. Bench-scale carbon-catalyst tests were conducted, to obtain kinetic rates of mercury adsorption (a key step in the catalytic oxidation of mercury by carbon) for different forms of carbon. All carbon types investigated behaved in a similar manner with respect to mercury sorption, including the effect of temperature and chlorine concentration. Activated carbon was more effective at adsorbing mercury than carbon black and unburned carbon (UBC), because their internal surface area of activated carbon was

  20. Surface Modified Coals for Enhanced Catalyst Dispersion and Liquefaction

    SciTech Connect

    Yaw D. Yeboah

    1998-12-04

    The aim of this study is to enhance catalyst loading and dispersion in coal for improved liquefaction by preadsorption of surfactants and catalysts on to the coal. During this reporting period, the effects of dodecyl dimethyl ethyl ammonium bromide (DDAB) (a cationic surfactant), sodium dodecyl sulfate (SDS) (an anionic surfactant), Triton X-100 (a neutral surfactant), and ferrous sulfate (as a catalyst precursor) on the coal surface charge at various pH values were determined. The results of the zeta potential measurements suggest that ferrous sulfate as catalyst precursor creates a distinctly different condition on the coal surface compared to that of molybdenum as reported in the previous progress reports. The effects of the adsorption of the surfactants also varied distinctly with the type of surfactant. With the adsorption of DDAB, the cationic surfactant, the surface charge was more positive. The opposite effect was observed for the SDS, the anionic surfactant. The coals treated with Triton X-100, the neutral surfactant, also showed an overall negative surface charge density. The adsorption of the catalyst precursor (ferrous sulfate) resulted in a net negative charge on the coal surface.

  1. Prolonging the hydration and active metabolism from light periods into nights substantially enhances lichen growth.

    PubMed

    Bidussi, Massimo; Gauslaa, Yngvar; Solhaug, Knut Asbjørn

    2013-05-01

    This study investigates how hydration during light and dark periods influences growth in two epiphytic old forest lichens, the green algal Lobaria pulmonaria and the cyanobacterial L. scrobiculata. The lichens were cultivated in growth chambers for 14 days (200 μmol m(-1) s(-2); 12 h photoperiod) at four temperature regimes (25/20 °C, 21/16 °C, 13/8 °C, and 6/1 °C; day/night temperatures) and two hydration regimes (12 h day-time hydration; 12 h day-time + 12 h night-time hydration). Growth was highly dynamic, showing that short-term growth experiments in growth cabinets have a high, but largely unexplored potential in functional lichen studies. The highest measured growth rates were not far from the maximal dry matter gain estimated from published net photosynthetic CO2 uptake data. For the entire data set, photobiont type, temperature, hydration regime and specific thallus mass accounted for 46.6 % of the variation in relative growth rate (RGR). Both species showed substantially higher relative growth rates based on both biomass (RGR) and thallus area (RTAGR) when they were hydrated day and night compared to hydration in light only. Chronic photoinhibition was substantial in thalli hydrated only during the day time and kept at the highest and lowest temperature regimes, resulting in exponential increases in RGR with increasing maximal PSII efficiency (F v/F m) in both species. However, the depression in F v/F m was stronger for the cyanolichen than for the cephalolichen at extreme temperatures. The growth-stimulating effect of night-time hydration suggests that nocturnal metabolic activity improves recovery of photoinhibition and/or enhances the conversion rate of photosynthates into thallus extension.

  2. Let physics substantiate music and music enhance physics- give principle to the other disciplines.

    NASA Astrophysics Data System (ADS)

    Chang, Hui-Yiing

    2006-03-01

    A conventional practice in K-12 education is to synchronize the arts and the sciences. Physics, traditionally been considered the mother of the sciences, and music, the mother of the arts, are interdependent and help to establishing a complete understanding of the other disciplines. Intense musical expression is attained when progression aims towards infinity. Motions are made in curves across time, imitating physical phenomena. The meaning of each element is enhanced according to the relative duration and dynamics of its context. Complete musical expression considers the three dimensions of space- length, breadth and height- and the three dimensions of time- past, present and future when balancing the instrumental parts and developing the structural elements. Overall, equilibrium is sought for like gravitational forces as expressed in equations. In learning processes, sensing precedes reasoning. Music attunes one to sensitive reactions towards the environment while physics substantiates the concepts by imposing a hierarchical order, the highest form of which is elegantly beautiful and most effectively expressed in music.

  3. SURFACE-MODIFIED COALS FOR ENHANCED CATALYST DISPERSION AND LIQUEFACTION

    SciTech Connect

    Dr. Yaw D. Yeboah

    1999-09-01

    This is the final report of the Department of Energy Sponsored project DE-FGF22-95PC95229 entitled, surface modified coals for enhanced catalyst dispersion and liquefaction. The aims of the study were to enhance catalyst loading and dispersion in coal for improved liquefaction by preadsorption of surfactants and catalysts on the coal and to train and educate minority scientists in catalysts and separation science. Illinois No. 6 Coal (DEC-24) was selected for the study. The surfactants investigated included dodecyl dimethyl ethyl ammonium bromide (DDAB), a cationic surfactant, sodium dodecyl sulfate, an anionic surfactant, and Triton x-100, a neutral surfactant. Ammonium molybdate tetrahydrate was used as the molybdenum catalyst precursor. Zeta potential, BET, FTIR, AFM, UV-Vis and luminescence intensity measurements were undertaken to assess the surface properties and the liquefaction activities of the coal. The parent coal had a net negative surface charge over the pH range 2-12. However, in the presence of DDAB the negativity of the surface charge decreased. At higher concentrations of DDAB, a positive surface charge resulted. In contrast to the effect of DDAB, the zeta potential of the coal became more negative than the parent coal in the presence of SDS. Adsorption of Triton reduced the net negative charge density of the coal samples. The measured surface area of the coal surface was about 30 m{sup 2}/g compared to 77m{sup 2}/g after being washed with deionized water. Addition of the surfactants decreased the surface area of the samples. Adsorption of the molybdenum catalyst increased the surface area of the coal sample. The adsorption of molybdenum on the coal was significantly promoted by preadsorption of DDAB and SDS. Molybdenum adsorption showed that, over a wide range of concentrations and pH values, the DDAB treated coal adsorbed a higher amount of molybdenum than the samples treated with SDS. The infrared spectroscopy (FTIR) and the atomic force

  4. Surface modified coals for enhanced catalyst dispersion and liquefaction

    SciTech Connect

    Dr. Yaw D. Yeboah

    1998-10-29

    The aim of the study is to enhance catalyst loading and dispersion in coal for improved liquefaction by preadsorption of surfactants and catalysts on to the coal. During this reporting period, zeta potential measurements were conducted to assess the surface charge on the raw, pretreated and catalyzed coal samples. The surface area, transmission spectroscopy and luminescence intensity of the raw coal and pretreated coal samples were also determined to assess the quality of the coal surface. Across a broad range of pH values, the raw coal had an overall negative charge. Coal treated with anionic surfactant SDS maintained an overall net negative surface negative charge. The interaction between the coal and cationic surfactant DDAB caused the opposite effect resulting in a more positive coal surface charge. Although one would have expected little or no effect of the neutral surfactant Triton X-100, there appears to be some difference in the results of the raw coal and the coal treated with Triton X-100. The authors believe that the Triton not only binds to the nonpolar sites but also has a strong affinity for the polar sites through electrostatic bonding and interaction between the hydrophobic tails. The addition of molybdenum to coal pretreated with DDAB caused a reduction in the positive charge of the coal surface probably due to possible ionic interaction between the coal surface, the surfactant and the catalyst. The adsorption isotherm of the coal was characteristic of isotherms for porous samples and the surface area of the coal increased from 30 m{sup 2}/g to 77 m{sup 2}/g when washed with deionized water. This suggests coal washing may be one method of increasing the surface area for surfactant adsorption. Although the transmission measurements provided valuable information about the coal it resulted in little information on the amount of adsorbed Triton. However, the maximum solid-liquid ratio for optimum surfactant loading of Triton X-100 was determined via

  5. Surface modified coals for enhanced catalyst and liquefaction

    SciTech Connect

    Abotsi, G.

    1997-12-31

    The aim of this work is to enhance catalyst loading and dispersion in coal for improved liquefaction by preadsorption of surfactants onto coal. Adsorption of the neutral surfactant Triton X-100 onto the coal (Illinois No. 6) followed by zeta potential measurements showed that the surfactant reduced the negative charge density on the coal surface. As was shown in the earlier reports, dodecyl dimethyl ethyl ammonium bromide (DDAB) rendered the surface positive whereas sodium dodecyl sulfate (SDS) increased the negative charge density on the coal. These findings are consistent with the fact that DDAB is cationic and SDS is anionic. Atomic force analysis of the raw coal and its samples treated with DDAB and SDS showed that the surface of the raw coal had large areas of roughness. However, adsorption of DDAB and molybdenum onto the coal resulted in the creation of a smooth surface with few isolated spots. This indicates that the surface of the coal is well covered by DDAB and may enhance the dispersion of the molybdenum catalyst. In contrast, examination of the SDS assisted molybdenum sample showed rod-like structures on the surface. Liquefaction studies showed that a total coal conversion of 96 wt.% was achieved when the coal was treated with Triton X-100 followed by molybdenum loading, compared with 89 wt% for the non-surfactant assisted molybdenum addition. The conversion of the raw, untreated coal in the absence of Triton and catalyst was 72 wt%. Thus, Triton X-100 appears to enhance the liquefaction activity of molybdenum. Liquefaction studies on DDAB and SDS samples will be conducted in subsequent experiments.

  6. Arginine-Containing Ligands Enhance H-2 Oxidation Catalyst Performance

    SciTech Connect

    Dutta, Arnab; Roberts, John A.; Shaw, Wendy J.

    2014-06-16

    In H2 fuel cells, performance depends on factors controlling turnover frequency and energy efficiency in the electrocatalytic oxidation of H2. Nature uses the hydrogenase enzymes to oxidize H2 at high turnover frequencies (up to 20,000 s-1) and low overpotentials (<100 mV), while the fastest synthetic catalyst reported to date only oxidizes H2 at 50 s-1 under 1 atm H2. Here we report a water-soluble complex incorporating the amino acid arginine, [NiII(PCy2NArg2)2]6+, that operates at 210 s-1 (180 mV overpotential) under 1 atm H2 and 144,000 s-1 (460 mV overpotential) under 133 atm H2. The complex functions from pH 0-14 with rates increasing at lower pH values. The arginine groups impart water solubility and play a critical role in enhancing turnover frequency, most consistent with an intramolecular Arg-Arg interaction that controls the structure of the catalyst active site. This work was funded by the Office of Science Early Career Research Program through the US DOE, BES (AD, WJS), and the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US DOE, BES (JASR). PNNL is operated by Battelle for the US DOE.

  7. Enhancement of alkylation catalysts for improved supercritical fluid regeneration

    DOEpatents

    Ginosar, Daniel M.; Petkovic, Lucia

    2009-09-22

    A method of modifying an alkylation catalyst to reduce the formation of condensed hydrocarbon species thereon. The method comprises providing an alkylation catalyst comprising a plurality of active sites. The plurality of active sites on the alkylation catalyst may include a plurality of weakly acidic active sites, intermediate acidity active sites, and strongly acidic active sites. A base is adsorbed to a portion of the plurality of active sites, such as the strongly acidic active sites, selectively poisoning the strongly acidic active sites. A method of modifying the alkylation catalyst by providing an alkylation catalyst comprising a pore size distribution that sterically constrains formation of the condensed hydrocarbon species on the alkylation catalyst or by synthesizing the alkylation catalyst to comprise a decreased number of strongly acidic active sites is also disclosed, as is a method of improving a regeneration efficiency of the alkylation catalyst.

  8. Enhancement of alkylation catalysts for improved supercritical fluid regeneration

    DOEpatents

    Ginosar, Daniel M.; Petkovic, Lucia M.

    2010-12-28

    A method of modifying an alkylation catalyst to reduce the formation of condensed hydrocarbon species thereon. The method comprises providing an alkylation catalyst comprising a plurality of active sites. The plurality of active sites on the alkylation catalyst may include a plurality of weakly acidic active sites, intermediate acidity active sites, and strongly acidic active sites. A base is adsorbed to a portion of the plurality of active sites, such as the strongly acidic active sites, selectively poisoning the strongly acidic active sites. A method of modifying the alkylation catalyst by providing an alkylation catalyst comprising a pore size distribution that sterically constrains formation of the condensed hydrocarbon species on the alkylation catalyst or by synthesizing the alkylation catalyst to comprise a decreased number of strongly acidic active sites is also disclosed, as is a method of improving a regeneration efficiency of the alkylation catalyst.

  9. Spatiotemporal Organization of Catalysts Driven by Enhanced Diffusion.

    PubMed

    Weistuch, C; Pressé, S

    2017-09-27

    Recently, both microfluidic and fluorescence correlation spectroscopy experiments have revealed that diffusion coefficients of active biological catalysts (enzymes) rise proportionately to their catalytic rate. Similar effects have also been observed for active material catalysts, such as platinum nanocatalysts in hydrogen peroxide solution. While differences in diffusion coefficients have recently been cleverly exploited to spatially separate active from inactive catalysts, here we investigate the consequences of these novel findings on the spatiotemporal organization of catalysts. In particular, we show that chemical reactions-such as coupled catalytic reactions-may drive effective attraction or repulsion between catalysts which in turn drives their spatiotemporal organization. This, we argue, may have implications for internal cell signaling.

  10. Enhancement of water-gas shift reaction efficiency: catalysts and the catalyst bed arrangement

    NASA Astrophysics Data System (ADS)

    Baronskaya, Natal'ya A.; Minyukova, Tat'yana P.; Khassin, Aleksandr A.; Yurieva, Tamara M.; Parmon, Valentin N.

    2010-12-01

    The results of studies devoted to the search for catalysts of water-gas shift (WGS) reaction that are highly active in a wide temperature interval are generalized. New compositions based on traditional and alternative, as regards the chemical composition, catalysts of high- and low-temperature WGS reaction are considered in detail. The single-stage arrangement of WGS reaction ensuring small temperature gradients in the radial direction of the catalyst bed are discussed.

  11. Catalyst Additives to Enhance Mercury Oxidation and Capture

    SciTech Connect

    Thomas K. Gale

    2005-12-31

    Preliminary research has shown that SCR catalysts employed for nitrogen-oxide reduction can effectively oxidize mercury. Three different SCR catalysts are currently being studied in this project--honeycomb-type, plate-type, and a hybrid-type catalyst. The catalysts were manufactured and supplied by Cormetech Inc., Hitachi America Ltd., and Haldor-Topsoe Inc., respectively. Parametric testing was performed to investigate the contribution of flue-gas chemistry on mercury oxidation via SCR catalysts. Future work to characterize flue gas simulations typically derived from low and high sulfur bituminous coal are being performed in a stepwise manner, to avoid the constant interruptions in testing that occur when leaks in the system are generated during temperature transitions. Specifically, chlorine concentration vs. mercury oxidation correlations will be developed for each catalyst. The contributions of temperature are also being investigated. SO2 oxidation is also being investigated for each test condition.

  12. Enhanced catalyst and process for converting synthesis gas to liquid motor fuels

    DOEpatents

    Coughlin, Peter K.

    1986-01-01

    The conversion of synthesis gas to liquid molar fuels by means of a cobalt Fischer-Tropsch catalyst composition is enhanced by the addition of molybdenum, tungsten or a combination thereof as an additional component of said composition. The presence of the additive component increases the olefinic content of the hydrocarbon products produced. The catalyst composition can advantageously include a support component, such as a molecular sieve, co-catalyst/support component or a combination of such support components.

  13. Catalyst Additives to Enhance Mercury Oxidation and Capture

    SciTech Connect

    Alex J. Berry; Thomas K. Gale

    2005-09-30

    Preliminary research has shown that SCR catalysts employed for nitrogen-oxide reduction can effectively oxidize mercury. This report discusses initial results from fundamental investigations into the behavior of mercury species in the presence of SCR catalysts at Southern Research Institute. The testing was performed at Southern Research's Catalyst Test Facility, a bench-scale reactor capable of simulating gas-phase reactions occurring in coal-fired utility pollution-control equipment. Three different SCR catalysts are currently being studied in this project - honeycomb-type, plate-type, and a hybrid-type catalyst. The catalysts were manufactured and supplied by Cormetech Inc., Hitachi America Ltd., and Haldor-Topsoe Inc., respectively. Parametric testing was performed to investigate the contribution of flue-gas chemistry on mercury oxidation via SCR catalysts. Methods and procedures for experimental testing continue to be developed to produce the highest quality mercury-oxidation data. Most experiments so far have focused on testing the catalysts in a simulated Powder River Basin (PRB) flue-gas environment, which contains lower sulfur and chlorine than produced by other coals. Future work to characterize flue gas simulations typically derived from low and high sulfur bituminous coal will be performed in a stepwise manner, to avoid the constant interruptions in testing that occur when leaks in the system are generated during temperature transitions. Specifically, chlorine concentration vs. mercury oxidation graph will be developed for each catalyst. The contributions of temperature and later sulfur will be investigated after this is complete. Also, last quarter's tests showed a potential linear relationship between SO3 conversion and mercury oxidation. As a result, SO3 samples will be taken more frequently to investigate each catalyst's ability to selectively oxidize mercury.

  14. SnO2 nanospheres supported Pd catalyst with enhanced performance for formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Lu, Haiting; Fan, Yang; Huang, Ping; Xu, Dongli

    2012-10-01

    SnO2 nanospheres were employed as the support material for Pd catalyst. The as-prepared Pd/SnO2 catalyst exhibited remarkably improved electrocatalytic activity and stability towards formic acid oxidation, in comparison with that of the Vulcan XC-72 carbon black and the commercial SnO2 nanopowder supported Pd catalyst. The enhanced catalytic performance may arise from the unique structure and surface properties of the SnO2 nanospheres, which process extraordinary promotional effect on Pd catalyst.

  15. Effects of catalyst film thickness on plasma-enhanced carbon nanotube growth

    SciTech Connect

    Hofmann, S.; Cantoro, M.; Kleinsorge, B.; Casiraghi, C.; Parvez, A.; Robertson, J.; Ducati, C.

    2005-08-01

    A systematic study is presented of the influence of catalyst film thickness on carbon nanostructures grown by plasma-enhanced chemical-vapor deposition from acetylene and ammonia mixtures. We show that reducing the Fe/Co catalyst film thickness below 3 nm causes a transition from larger diameter (>40 nm), bamboolike carbon nanofibers to small diameter ({approx}5 nm) multiwalled nanotubes with two to five walls. This is accompanied by a more than 50 times faster growth rate and a faster catalyst poisoning. Thin Ni catalyst films only trigger such a growth transition when pretreated with an ammonia plasma. We observe a limited correlation between this growth transition and the coarsening of the catalyst film before deposition. For a growth temperature of {<=}550 deg. C, all catalysts showed mainly a tip growth regime and a similar activity on untreated silicon, oxidized silicon, and silicon nitride support.

  16. Method for generating a highly reactive plasma for exhaust gas after treatment and enhanced catalyst reactivity

    SciTech Connect

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2000-07-01

    This patent application describes a method and apparatus of exhaust gas remediation that enhance the reactivity of the material catalysts found within catalytic converters of cars, trucks, and power stations.

  17. Novel Intermetallic Catalysts to Enhance PEM Membrane Durability

    SciTech Connect

    Francis J. DiSalvo

    2009-01-06

    The research examined possible sources of degradation of platinum based anode catalysts under long term use. Scientists at the United Technologies Research Center had shown that the anode as well as the cathode catalysts degrade in hydrogen fuel cells. This goal of this research was to see if mechanisms of anode degradation could be understood using forefront electrochemical techniques in an aqueous system. We found that this method is limited by the very low levels of impurities (perhaps less than a part per trillion) in the electrolyte. This limitation comes from the relatively small catalyst surface area (a few sq cm or less) compared to the electrolyte volume of 10 to 25 ml. In real fuel cells this ratio is completelyreversed: high catalyst surface area and low electrolyte violume, making the system much less sensitive to impurities in the electrolyte. We conclude that degradation mechanisms should be studied in real fuel cell systems, rather than in ex-situ, large electrolyte volume experiments.

  18. Decomposition studies of filtered slurries using the enhanced comprehensive catalyst

    SciTech Connect

    Wilmarth, W.R.; Crawford, C.L.; Peterson, R.A.

    1997-11-13

    This study examined decomposition of the soluble phenylborates at elevated temperatures (45 degrees Celsius) to determine the effects of filtering the solid tetraphenylborate, solid sludge and monosodium titanate and spiking additional levels of transition metal catalyst.

  19. Catalyst Additives to Enhance Mercury Oxidation and Capture

    SciTech Connect

    Jared W. Cannon; Thomas K. Gale

    2005-06-30

    Preliminary research has shown that SCR catalysts employed for nitrogen-oxide reduction can effectively oxidize mercury. This report discusses initial results from fundamental investigations into the behavior of mercury species in the presence of SCR catalysts at Southern Research Institute. The testing was performed at Southern Research's Catalyst Test Facility, a bench-scale reactor capable of simulating gas-phase reactions occurring in coal-fired utility pollution-control equipment. Three different SCR catalysts are currently being studied in this project--honeycomb-type, plate-type, and a hybrid-type catalyst. The catalysts were manufactured and supplied by Cormetech Inc., Hitachi America Ltd., and Haldor-Topsoe Inc., respectively. Parametric testing was performed to investigate the contribution of flue-gas chemistry on mercury oxidation via SCR catalysts. Methods and procedures for experimental testing continue to be developed to produce the highest quality mercury-oxidation data. During this past quarter, it was discovered that long periods (12 - 24 hours) are required to equilibrate the catalysts in the system. In addition, after the system has been equilibrated, operational changes to temperature, gas concentration, or flow rate shifts the equilibrium, and steady-state must be reestablished, which can require as much as twelve additional hours per condition change. In the last quarter of testing, it was shown that the inclusion of ammonia had a strong effect on the oxidation of mercury by SCR catalysts, both in the short-term (a transitional period of elemental and oxidized mercury off gassing) and the long-term (less steady-state mercury oxidation). All experiments so far have focused on testing the catalysts in a simulated Powder River Basin (PRB) flue-gas environment, which contains lower sulfur and chlorine than produced by other coals. In the next quarter, parametric testing will be expanded to include flue gases simulating power plants burning

  20. Method for generating a highly reactive plasma for exhaust gas aftertreatment and enhanced catalyst reactivity

    DOEpatents

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2002-01-01

    A method for non-thermal plasma aftertreatment of exhaust gases the method comprising the steps of providing short risetime, high frequency, high power bursts of low-duty factor microwaves sufficient to generate a plasma discharge and passing a gas to be treated through the discharge so as to cause dissociative reduction of the exhaust gases and enhanced catalyst reactivity through application of the pulsed microwave fields directly to the catalyst material sufficient to cause a polarizability catastrophe and enhanced heating of the metal crystallite particles of the catalyst, and in the presence or absence of the plasma. The invention also includes a reactor for aftertreatment of exhaust gases.

  1. Highly dispersed metal catalyst

    DOEpatents

    Xiao, Xin; West, William L.; Rhodes, William D.

    2016-11-08

    A supported catalyst having an atomic level single atom structure is provided such that substantially all the catalyst is available for catalytic function. A process of forming a single atom catalyst unto a porous catalyst support is also provided.

  2. Substantial gain enhancement for optical parametric amplification and oscillation in two-dimensional chi(2) nonlinear photonic crystals.

    PubMed

    Liu, Hsi-Chun; Kung, A H

    2008-06-23

    We have analyzed optical parametric interaction in a 2D NPC. While in general the nonlinear coefficient is small compared to a 1D NPC, we show that at numerous orientations a multitude of reciprocal vectors contribute additively to enhance the gain in optical parametric amplification and oscillation in a 2D patterned crystal. In particular, we have derived the effective nonlinear coefficients for common-signal amplification and common-idler amplification for a tetragonal inverted domain pattern. We show that in the specific case of signal amplification with QPM by both G(10) and G(11), symmetry of the crystal results in coupled interaction with the corresponding signal amplification by G(10) and G(1,-1). As a consequence, this coupled utilization of all three reciprocal vectors leads to a substantial increase in parametric gain. Using PPLN we demonstrate numerically that a gain that comes close to that of a 1D QPM crystal could be realized in a 2D NPC with an inverted tetragonal domain pattern. This special mechanism produces two pairs of identical signal and idler beams propagating in mirror-imaged forward directions. In conjunction with this gain enhancement and multiple beams output we predict that there is a large pulling effect on the output wavelength due to dynamic signal build-up in the intrinsic noncollinear geometry of a 2D NPC OPO.

  3. Catalyst design for enhanced sustainability through fundamental surface chemistry.

    PubMed

    Personick, Michelle L; Montemore, Matthew M; Kaxiras, Efthimios; Madix, Robert J; Biener, Juergen; Friend, Cynthia M

    2016-02-28

    Decreasing energy consumption in the production of platform chemicals is necessary to improve the sustainability of the chemical industry, which is the largest consumer of delivered energy. The majority of industrial chemical transformations rely on catalysts, and therefore designing new materials that catalyse the production of important chemicals via more selective and energy-efficient processes is a promising pathway to reducing energy use by the chemical industry. Efficiently designing new catalysts benefits from an integrated approach involving fundamental experimental studies and theoretical modelling in addition to evaluation of materials under working catalytic conditions. In this review, we outline this approach in the context of a particular catalyst-nanoporous gold (npAu)-which is an unsupported, dilute AgAu alloy catalyst that is highly active for the selective oxidative transformation of alcohols. Fundamental surface science studies on Au single crystals and AgAu thin-film alloys in combination with theoretical modelling were used to identify the principles which define the reactivity of npAu and subsequently enabled prediction of new reactive pathways on this material. Specifically, weak van der Waals interactions are key to the selectivity of Au materials, including npAu. We also briefly describe other systems in which this integrated approach was applied.

  4. Enhancing oxygen reduction reaction activity of Pt-shelled catalysts via subsurface alloying.

    PubMed

    Cheng, Daojian; Qiu, Xiangguo; Yu, Haiyan

    2014-10-14

    Despite remarkable efforts have been put into the field of Pt-shelled catalysts containing an atomically thin Pt surface layer for the oxygen reduction reaction (ORR) in the last decade, further development of new Pt-shelled catalysts is still necessary. Here, a new set of Pt-shelled catalysts by subsurface alloying with early transition metals such as Mn and Fe is predicted to be a good candidate for the ORR by using density functional theory (DFT) calculations. Trends in oxygen reduction activity of Pt-alloy catalysts are determined with calculations of oxygen binding by using the slab and cluster models. It is found that the subsurface alloys by the incorporation of submonolayer M (M = Mn and Fe) into Pt(111) in the slab model result in the enhancement of ORR activity, compared with the well-known Pt(111)-skin-M, pure Pt, and Pt3M alloy catalysts. For the cluster model, the Pt12Mn and Pt12Fe clusters are also found to be the optimal catalysts for the ORR. It is expected that this work can open up new opportunities for enhancing the ORR activity of Pt-alloy catalysts by subsurface alloying.

  5. Robust Resilience and Substantial Interest: A Survey of Pharmacological Cognitive Enhancement among University Students in the UK and Ireland

    PubMed Central

    Singh, Ilina; Bard, Imre; Jackson, Jonathan

    2014-01-01

    Use of ‘smart drugs’ among UK students is described in frequent media reports as a rapidly increasing phenomenon. This article reports findings from the first large-scale survey of pharmacological cognitive enhancement (PCE) among students in the UK and Ireland. Conducted from February to September 2012, a survey of a convenience sample of 877 students measured PCE prevalence, attitudes, sources, purposes and ethics. Descriptive and logistic regression statistical methods were used to analyse the data. Lifetime prevalence of PCE using modafinil, methylphenidate or Adderall was under 10%, while past regular and current PCE users of these substances made up between 0.3%–4% of the survey population. A substantial majority of students was unaware of and/or uninterested in PCE; however about one third of students were interested in PCE. PCE users were more likely to be male, British and older students; predictors of PCE use included awareness of other students using PCEs, ADHD symptomatology, ethical concerns, and alcohol and cannabis use. The survey addresses the need for better evidence about PCE prevalence and practices among university students in the UK. We recommend PCE-related strategies for universities based on the survey findings. PMID:25356917

  6. Photo-oxidation catalysts

    DOEpatents

    Pitts, J. Roland; Liu, Ping; Smith, R. Davis

    2009-07-14

    Photo-oxidation catalysts and methods for cleaning a metal-based catalyst are disclosed. An exemplary catalyst system implementing a photo-oxidation catalyst may comprise a metal-based catalyst, and a photo-oxidation catalyst for cleaning the metal-based catalyst in the presence of light. The exposure to light enables the photo-oxidation catalyst to substantially oxidize absorbed contaminants and reduce accumulation of the contaminants on the metal-based catalyst. Applications are also disclosed.

  7. Enhanced Fuel Cell Catalyst Durability with Nitrogen Modified Carbon Supports

    DTIC Science & Technology

    2013-02-12

    materials. enrichment in ruthenium with the N-modified samples as compared to the non-implanted commercial and in-house sputtered samples. Over- all we...found a major difference between commercial and sputtered samples with respect to their ruthenium compositions with the results summarized in Table I. In...commercial catalysts, surface ruthenium is distributed between metallic ruthenium (Ru(0), Ru(II), Ru(IV), ruthe- nium oxide RuO2 and hydrous ruthenium

  8. Enhanced High Temperature Performance of NOx Reduction Catalyst Materials

    SciTech Connect

    Gao, Feng; Kim, Do Heui; Luo, Jinyong; Muntean, George G.; Peden, Charles HF; Howden, Ken; Currier, Neal; Kamasamudram, Krishna; Kumar, Ashok; Li, Junhui; Stafford, Randy; Yezerets, Aleksey; Castagnola, Mario; Chen, Hai Ying; Hess, Howard ..

    2012-12-31

    Two primary NOx after-treatment technologies have been recognized as the most promising approaches for meeting stringent NOx emission standards for diesel vehicles within the Environmental Protection Agency’s (EPA’s) 2007/2010 mandated limits, NOx Storage Reduction (NSR) and NH3 selective catalytic reduction (SCR); both are, in fact being commercialized for this application. However, in looking forward to 2015 and beyond with expected more stringent regulations, the continued viability of the NSR technology for controlling NOx emissions from lean-burn engines such as diesels will require at least two specific, significant and inter-related improvements. First, it is important to reduce system costs by, for example, minimizing the precious metal content while maintaining, even improving, performance and long-term stability. A second critical need for future NSR systems, as well as for NH3 SCR, will be significantly improved higher and lower temperature performance and stability. Furthermore, these critically needed improvements will contribute significantly to minimizing the impacts to fuel economy of incorporating these after-treatment technologies on lean-burn vehicles. To meet these objectives will require, at a minimum an improved scientific understanding of the following things: i) the various roles for the precious and coinage metals used in these catalysts; ii) the mechanisms for these various roles; iii) the effects of high temperatures on the active metal performance in their various roles; iv) mechanisms for higher temperature NOx storage performance for modified and/or alternative storage materials; v) the interactions between the precious metals and the storage materials in both optimum NOx storage performance and long term stability; vi) the sulfur adsorption and regeneration mechanisms for NOx reduction materials; vii) materials degradation mechanisms in CHA-based NH3 SCR catalysts. The objective of this CRADA project between PNNL and Cummins, Inc

  9. Enhanced Activity of Supported Ni Catalysts Promoted by Pt for Rapid Reduction of Aromatic Nitro Compounds

    PubMed Central

    Shang, Huishan; Pan, Kecheng; Zhang, Lu; Zhang, Bing; Xiang, Xu

    2016-01-01

    To improve the activities of non-noble metal catalysts is highly desirable and valuable to the reduced use of noble metal resources. In this work, the supported nickel (Ni) and nickel-platinum (NiPt) nanocatalysts were derived from a layered double hydroxide/carbon composite precursor. The catalysts were characterized and the role of Pt was analysed using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS) mapping, and X-ray photoelectron spectroscopy (XPS) techniques. The Ni2+ was reduced to metallic Ni0 via a self-reduction way utilizing the carbon as a reducing agent. The average sizes of the Ni particles in the NiPt catalysts were smaller than that in the supported Ni catalyst. The electronic structure of Ni was affected by the incorporation of Pt. The optimal NiPt catalysts exhibited remarkably improved activity toward the reduction of nitrophenol, which has an apparent rate constant (Ka) of 18.82 × 10−3 s−1, 6.2 times larger than that of Ni catalyst and also larger than most of the reported values of noble-metal and bimetallic catalysts. The enhanced activity could be ascribed to the modification to the electronic structure of Ni by Pt and the effect of exposed crystal planes. PMID:28335231

  10. Enhanced Activity of Supported Ni Catalysts Promoted by Pt for Rapid Reduction of Aromatic Nitro Compounds.

    PubMed

    Shang, Huishan; Pan, Kecheng; Zhang, Lu; Zhang, Bing; Xiang, Xu

    2016-06-04

    To improve the activities of non-noble metal catalysts is highly desirable and valuable to the reduced use of noble metal resources. In this work, the supported nickel (Ni) and nickel-platinum (NiPt) nanocatalysts were derived from a layered double hydroxide/carbon composite precursor. The catalysts were characterized and the role of Pt was analysed using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS) mapping, and X-ray photoelectron spectroscopy (XPS) techniques. The Ni(2+) was reduced to metallic Ni⁰ via a self-reduction way utilizing the carbon as a reducing agent. The average sizes of the Ni particles in the NiPt catalysts were smaller than that in the supported Ni catalyst. The electronic structure of Ni was affected by the incorporation of Pt. The optimal NiPt catalysts exhibited remarkably improved activity toward the reduction of nitrophenol, which has an apparent rate constant (Ka) of 18.82 × 10(-3) s(-1), 6.2 times larger than that of Ni catalyst and also larger than most of the reported values of noble-metal and bimetallic catalysts. The enhanced activity could be ascribed to the modification to the electronic structure of Ni by Pt and the effect of exposed crystal planes.

  11. Enhancement in Rate of Photocatalysis Upon Catalyst Recycling

    NASA Astrophysics Data System (ADS)

    Sorathiya, Kalpesh; Mishra, Biswajit; Kalarikkal, Abhishek; Reddy, Kasala Prabhakar; Gopinath, Chinnakonda S.; Khushalani, Deepa

    2016-10-01

    Recyclability is an important aspect for heterogeneous photo-catalysts. Ease of recovery and stability of the photo-catalyst in terms of efficiency over the number of cycles are highly desired and in fact it is ideal if the efficiency is constant and it should not decrease marginally with each cycle. Presented here is a seminal observation in which the photocatalytic activity is shown to improve with increasing number of catalytic cycles (it is 1.7 times better after the 1st cycle and 3.1 times better after the 2nd cycle). Specifically, nanorods of pure TiO2 and TiO2 doped with controlled amount of tungsten have been used to degrade two model pollutants: Phenol and Rhodamine B under exclusive visible light illumination. It was found that, in case of 1 mol.% W incorporation, rate of photocatalysis and also the range of visible light absorption of the photocatalyst increased after the photocatalysis as compared to before photocatalysis. This aspect is unique for doped TiO2 and hence provides an intriguing way to mitigate low photoactivity.

  12. Enhancement in Rate of Photocatalysis Upon Catalyst Recycling

    PubMed Central

    Sorathiya, Kalpesh; Mishra, Biswajit; Kalarikkal, Abhishek; Reddy, Kasala Prabhakar; Gopinath, Chinnakonda S.; Khushalani, Deepa

    2016-01-01

    Recyclability is an important aspect for heterogeneous photo-catalysts. Ease of recovery and stability of the photo-catalyst in terms of efficiency over the number of cycles are highly desired and in fact it is ideal if the efficiency is constant and it should not decrease marginally with each cycle. Presented here is a seminal observation in which the photocatalytic activity is shown to improve with increasing number of catalytic cycles (it is 1.7 times better after the 1st cycle and 3.1 times better after the 2nd cycle). Specifically, nanorods of pure TiO2 and TiO2 doped with controlled amount of tungsten have been used to degrade two model pollutants: Phenol and Rhodamine B under exclusive visible light illumination. It was found that, in case of 1 mol.% W incorporation, rate of photocatalysis and also the range of visible light absorption of the photocatalyst increased after the photocatalysis as compared to before photocatalysis. This aspect is unique for doped TiO2 and hence provides an intriguing way to mitigate low photoactivity. PMID:27731347

  13. Enhancement in Rate of Photocatalysis Upon Catalyst Recycling.

    PubMed

    Sorathiya, Kalpesh; Mishra, Biswajit; Kalarikkal, Abhishek; Reddy, Kasala Prabhakar; Gopinath, Chinnakonda S; Khushalani, Deepa

    2016-10-12

    Recyclability is an important aspect for heterogeneous photo-catalysts. Ease of recovery and stability of the photo-catalyst in terms of efficiency over the number of cycles are highly desired and in fact it is ideal if the efficiency is constant and it should not decrease marginally with each cycle. Presented here is a seminal observation in which the photocatalytic activity is shown to improve with increasing number of catalytic cycles (it is 1.7 times better after the 1(st) cycle and 3.1 times better after the 2(nd) cycle). Specifically, nanorods of pure TiO2 and TiO2 doped with controlled amount of tungsten have been used to degrade two model pollutants: Phenol and Rhodamine B under exclusive visible light illumination. It was found that, in case of 1 mol.% W incorporation, rate of photocatalysis and also the range of visible light absorption of the photocatalyst increased after the photocatalysis as compared to before photocatalysis. This aspect is unique for doped TiO2 and hence provides an intriguing way to mitigate low photoactivity.

  14. Study of nickel catalysts for hydrogen production in sorption enhanced reforming process

    NASA Astrophysics Data System (ADS)

    García-Lario, Ana L.; Aznar, María; Grasa, Gemma S.; García, Tomás; Murillo, Ramón

    2013-11-01

    The performance of Ni based catalysts to be used in Sorption Enhanced Reforming (SER) is assessed. For this aim, both their activity at low temperature and their behavior during multiple oxidation-reduction cycles in steam methane reforming are studied. Ni catalysts supported on α-Al2O3, Si3N4 and NiAl2O4, with different amounts of Ni (0-50% NiO), are compared by testing their activity in a fixed bed micro-reactor. While Ni/Si3N4 catalysts do not show an appropriate performance at low temperature, Ni/α-Al2O3 and Ni/NiAl2O4 present a significant activity, close to equilibrium data, at the typical SER conditions. The best experimental results are attained for 20% NiO/α-Al2O3 and 10% NiO/NiAl2O4 catalysts that show an activity close to the equilibrium for steam to methane ratio of 4.5. Higher amounts of NiO in both catalysts do not reveal an improvement in conversion results. In addition, both 20% NiO/α-Al2O3 and 10% NiO/NiAl2O4 catalysts show a good reforming activity after oxidation-reduction cycles at typical SER temperatures. The observed trend to carbon deposition on the catalyst surface for the studied supports is Si3N4 > Al2O3 > NiAl2O4, being negligible when NiAl2O4 support is used. These results suggested that 10% NiO/NiAl2O4 and 20% NiO/Al2O3 catalysts could be perfect candidates to be used in SER process.

  15. Single-Atom Pt as Co-Catalyst for Enhanced Photocatalytic H2 Evolution.

    PubMed

    Li, Xiaogang; Bi, Wentuan; Zhang, Lei; Tao, Shi; Chu, Wangsheng; Zhang, Qun; Luo, Yi; Wu, Changzheng; Xie, Yi

    2016-03-23

    Isolated single-atom platinum (Pt) embedded in the sub-nanoporosity of 2D g-C3 N4 as a new form of co-catalyst is reported. The highly stable single-atom co-catalyst maximizes the atom efficiency and alters the surface trap states of g-C3 N4 , leading to significantly enhanced photocatalytic H2 evolution activity, 8.6 times higher than that of Pt nanoparticles and up to 50 times that for bare g-C3 N4 .

  16. Catalyst Additives to Enhance Mercury Oxidation and Capture

    SciTech Connect

    Thomas K. Gale

    2004-09-30

    Bench-scale carbon-catalyst tests were conducted in the first quarter of 2004, to obtain kinetic rates of mercury oxidation and sorption for different forms of carbon. The current quarterly report provides a more extensive quantitative analysis of the data obtained from the CRTF experiments on different carbon types and carbocalcium mixtures than was presented in the last quarterly report. The procedure and basis for normalizing mercury removals, so that they could be compared on an equal residence time basis, is described. The chemisorption rate of mercury on carbon was found to be first order in mercury concentration and half order in HCl concentration, for the facility configuration investigated. The applicable temperature range of the kinetic rates obtained is from 300 F to 700 F, and the applicable chlorine concentration range is from 2 ppmv HCl to 250 ppmv HCl. The gas-sorbent contact time of 0.12 seconds used in this work was shown to be representative of gas-dust cake contact times in full-scale baghouses. All carbon types investigated behaved similarly with respect to Hg sorption, including the effect of temperature and chlorine concentration. Activated carbon was more effective at sorbing mercury than carbon black and unburned carbon (UBC), because the internal surface area of activated carbon is greater. The synergistic relationship between Ca and C is also discussed in the report.

  17. A novel catalyst of warm-cloud seeding to enhance precipitation

    NASA Astrophysics Data System (ADS)

    Zhu, H. X.; Li, X. D.; Yang, R. J.

    2016-07-01

    Water is necessary for sustaining human life. In many regions of the world, traditional water sources cannot meet increasing water demands. Warm-cloud seeding is an efficient way to augment water supplies. In this paper, we explore two new hygroscopicity catalysts: Poly acrylamide (PAM) and Sodium polyacrylate (PAAS). We designed a series of experiments to investigate the effects of these catalysts together with common catalyst salt powder (NaCl). The experiment was held in a cloud chamber built in our laboratory. The results show that: 1) Catalysed by NaCl, a dose of 0.91g/m3 can obtain the best precipitation efficiency and enhancement rate at 70.8% and 142%, respectively; 2) A 1.36g/m3 dose catalysed by PAM and PAAS exhibits optimal performance at 76.7% and 70.4% precipitation efficiency, respectively; 3) Under the same conditions, PAM shows better catalytic effects than NaCl does.

  18. Enhancement of interfacial catalysis in a biphasic system using catalyst-binding ligands

    NASA Astrophysics Data System (ADS)

    Chaudhari, R. V.; Bhanage, B. M.; Deshpande, R. M.; Delmas, H.

    1995-02-01

    TO avoid the problem of separation of products from catalyst in homogeneous catalysis1, two-phase systems have been developed in which the catalytic complex (usually a water-soluble organo-metallic complex) remains in one (generally aqueous) phase while the products remain in a second, immiscible phase2. Catalysis relies on the transfer of organic substrates into the aqueous catalyst phase; but the limited solubility of these substrates in water leads to reaction rates much lower than those for conventional homo-geneous catalysis. Here we show that catalysis at the interface of a two-phase system can be enhanced by using a 'promoter ligand' which, although soluble in the organic phase, will bind to the organometallic catalyst and thus increase its concentration close to the interface in the aqueous phase. We demonstrate this approach for the hydroformylation of 1-octene using a rhodium-based catalyst. A rate enhancement by a factor of 10-50 is observed when we introduce the promoter ligand PPh3 in the organic phase.

  19. Enhanced electrocatalytic activity of CoTMPP-based catalysts for PEMFCs by plasma treatment

    NASA Astrophysics Data System (ADS)

    Savastenko, N. A.; Brüser, V.; Brüser, M.; Anklam, K.; Kutschera, S.; Steffen, H.; Schmuhl, A.

    In this work, we developed a methodology of plasma-enhanced preparation of CoTMPP (tetramethoxyphenylporphyrin)-based electrocatalysts. A series of CoTMPP-based electrocatalysts were deposited on the porous gas diffusion substrate (titanium fibre felt) using plasma-enhanced impregnation method. Impregnated 1.5 mg cm -2 CoTMPP/Ti catalysts were treated by dielectric barrier discharge (DBD) plasma in Ar or N 2 atmosphere. Additionally, the pretreatment methods were utilized to improve the adhesion of CoTMPP on the diffusion layer surface. The plasma pretreatment methods included the a-C:H-layers deposition followed by an Ar:O 2 radio frequency (RF) plasma functionalization. The latter approach led to the formation of specific oxygen surface groups that influenced the catalysts activity. Obtained catalysts were compared in terms of activity, stability and structure. The catalytic activity for hydrogen peroxide (H 2O 2) reduction was tested in a proton exchange membrane fuel cell (PEMFC) using hydrogen peroxide on the cathode side. Surface elemental analysis and structure of catalysts were examined by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Our contribution shows the potential of a plasma treatment in the preparation of electrocatalysts for hydrogen peroxide reduction reaction in a PEMFC. Under the conditions of this study, improvement of the PEMFC performance up to 30% was achievable by a deposition of CoTMPP on the titanium diffusion substrate followed by plasma treatment. The large differences in catalytic activity of CoTMPP/Ti were observed, depending on the plasma treatment applied to the catalysts during their preparation.

  20. Design of Ternary Nanoalloy Catalysts: Effect of Nanoscale Alloying and Structural Perfection on Electrocatalytic Enhancement

    SciTech Connect

    Wanjala, Bridgid N.; Fang, Bin; Shan, Shiyao; Petkov, Valeri; Zhu, Pengyu; Loukrakpam, Rameshwori; Chen, Yongsheng; Luo, Jin; Yin, Jun; Yang, Lefu; Shao, Minhua; Zhong, Chuan-Jian

    2012-10-22

    The ability to tune the atomic-scale structural and chemical ordering in nanoalloy catalysts is essential for achieving the ultimate goal of high activity and stability of catalyst by design. This article shows this ability with a ternary nanoalloy of platinum with vanadium and cobalt for oxygen reduction reaction in fuel cells. The strategy is to enable nanoscale alloying and structural perfection through oxidative–reductive thermochemical treatments. The structural manipulation is shown to produce a significant enhancement in the electrocatalytic activity of the ternary nanoalloy catalysts for oxygen reduction reaction. Mass activities as high as 1 A/mg of Pt have been achieved by this strategy based on direct measurements of the kinetic currents from rotating disk electrode data. Using a synchrotron high-energy X-ray diffraction technique coupled with atomic pair function analysis and X-ray absorption fine structure spectroscopy as well as X-ray photoelectron spectroscopy, the atomic-scale structural and chemical ordering in nanoalloy catalysts prepared by the oxidative–reductive thermochemical treatments were examined. A phase transition has been observed, showing an fcc-type structure of the as-prepared and the lower-temperature-treated particles into an fct-type structure for the particles treated at the higher temperature. The results reveal a thermochemically driven evolution of the nanoalloys from a chemically disordered state into chemically ordered state with an enhanced degree of alloying. The increase in the chemical ordering and shrinking of interatomic distances as a result of thermochemical treatment at increased temperature is shown to increase the catalytic activity for oxygen reduction reaction, exhibiting an optimal activity at 600 °C. It is the alloying and structural perfection that allows the optimization of the catalytic performance in a controllable way, highlighting the significant role of atomic-scale structural and chemical ordering

  1. Design of Ternary Nanoalloy Catalysts: Effect of Nanoscale Alloying and Structural Perfection on Electrocatalytic Enhancement

    SciTech Connect

    Wanjala, Bridgid N.; Fang, Bin; Shan, Shiyao; Petkov, Valeri; Zhu, Pengyu; Loukrakpam, Rameshwori; Chen, Yongsheng; Luo, Jin; Yin, Jun; Yang, Lefu; Shao, Minhua; Zhong, Chuan-Jian

    2012-11-27

    The ability to tune the atomic-scale structural and chemical ordering in nanoalloy catalysts is essential for achieving the ultimate goal of high activity and stability of catalyst by design. This article demonstrates this ability with a ternary nanoalloy of platinum with vanadium and cobalt for oxygen reduction reaction in fuel cells. The strategy is to enable nanoscale alloying and structural perfection through oxidative–reductive thermochemical treatments. The structural manipulation is shown to produce a significant enhancement in the electrocatalytic activity of the ternary nanoalloy catalysts for oxygen reduction reaction. Mass activities as high as 1 A/mg of Pt have been achieved by this strategy based on direct measurements of the kinetic currents from rotating disk electrode data. Using a synchrotron high-energy X-ray diffraction technique coupled with atomic pair function analysis and X-ray absorption fine structure spectroscopy as well as X-ray photoelectron spectroscopy, the atomic-scale structural and chemical ordering in nanoalloy catalysts prepared by the oxidative–reductive thermochemical treatments were examined. A phase transition has been observed, showing an fcc-type structure of the as-prepared and the lower-temperature-treated particles into an fct-type structure for the particles treated at the higher temperature. The results reveal a thermochemically driven evolution of the nanoalloys from a chemically disordered state into chemically ordered state with an enhanced degree of alloying. The increase in the chemical ordering and shrinking of interatomic distances as a result of thermochemical treatment at increased temperature is shown to increase the catalytic activity for oxygen reduction reaction, exhibiting an optimal activity at 600 °C. It is the alloying and structural perfection that allows the optimization of the catalytic performance in a controllable way, highlighting the significant role of atomic-scale structural and chemical

  2. Enhancement of Pt/SnO2 Catalysts by Addition of H2O

    NASA Technical Reports Server (NTRS)

    Schryer, David R.; Sidney, Barry D.; Van Norman, John D.; Brown, Kenneth G.; Schryer, Jacqueline; Upchurch, Billy T.

    1990-01-01

    Water vapor in pretreatment gas restores essential hydroxyl groups. Platinum on tin oxide (Pt/SnO2) is good catalyst for oxidation of carbon monoxide (CO) at temperatures from about 25 degrees C to 100 degress C. Activity of Pt/SnO2 for CO oxidation significantly enhanced by pretreating it at approximately 225 degrees C with reducing gas such as CO. Technique useful in manufacture of high-power CO2 lasers for industrial and scientific uses.

  3. Enhancement of Pt/SnO2 Catalysts by Addition of H2O

    NASA Technical Reports Server (NTRS)

    Schryer, David R.; Sidney, Barry D.; Van Norman, John D.; Brown, Kenneth G.; Schryer, Jacqueline; Upchurch, Billy T.

    1990-01-01

    Water vapor in pretreatment gas restores essential hydroxyl groups. Platinum on tin oxide (Pt/SnO2) is good catalyst for oxidation of carbon monoxide (CO) at temperatures from about 25 degrees C to 100 degress C. Activity of Pt/SnO2 for CO oxidation significantly enhanced by pretreating it at approximately 225 degrees C with reducing gas such as CO. Technique useful in manufacture of high-power CO2 lasers for industrial and scientific uses.

  4. Significant color space blue-shift of green OLED emitter with sustaining lifetime and substantial efficiency enhancement

    NASA Astrophysics Data System (ADS)

    Li, Jung-Yu; Chen, Shih-Pu; Siao, Huei-Jhen; Wu, Jin-Han; Chen, Guan-Yu; Chen, Cheng-Chang; Ho, Shu-Yi; Lin, Yi-Ping; Hsu, Hong-Hui; Lin, Jin-Sheng; Jeng, Ming-Shan; Chen, Nai-Chuan; Zeng, Hui-Kai; Juang, Jenh-Yih

    2017-08-01

    In this study, we demonstrate that by embedding a plasmonic coupling metal layer beneath the active layer of an organic light-emitting diode, the resultant device is capable of inducing significant blue shifts in CIE color space coordinates of emitting light from the green emitting material without compromising the lifetime of the parent material. The implemented device consists of multilayers of organic emitting materials sandwiched by two thin metal layers to form a metal-dielectric-metal (MDM) cavity-like structure. The original green emission with CIE coordinates of (0.22, 0.56) was significantly color space blue-shifted to CIE coordinates of (0.10, 0.53). The MDM device exhibits an efficiency of 62 cd/A at a luminance of 1000 cd/m2, which represents a two-fold enhancement of current efficiency. Moreover, the spectral peak intensity is 4.3 times higher than that in a conventional device, which is much higher than that expected for an optical microcavity model, suggesting that the Purcell effect resulting from the coupling of surface plasmon waves may contribute to the extra enhancement of emission intensity.

  5. Enhanced formic acid electro-oxidation reaction on ternary Pd-Ir-Cu/C catalyst

    NASA Astrophysics Data System (ADS)

    Chen, Jinwei; Zhang, Jie; Jiang, Yiwu; Yang, Liu; Zhong, Jing; Wang, Gang; Wang, Ruilin

    2015-12-01

    Aim to further reduce the cost of Pd-Ir for formic acid electro-oxidation (FAEO), the Cu was used to construct a ternary metallic alloy catalyst. The prepared catalysts are characterized using XRD, TGA, EDX, TEM, XPS, CO-stripping, cyclic voltammetry and chronoamperometry. It is found that the Pd18Ir1Cu6 nanoparticles with a mean size of 3.3 nm are highly dispersed on carbon support. Componential distributions on catalyst are consistent with initial contents. Electrochemical measurements show that the PdIrCu/C catalyst exhibits the highest activity for FAEO. The mass activity of Pd in Pd18Ir1Cu6/C at 0.16 V (vs. SCE) is about 1.47, 1.62 and 2.08 times as high as that of Pd18Cu6/C, Pd18Ir1/C and Pd/C, respectively. The activity enhancement of PdIrCu/C should be attributed to the weakened CO adsorption strength and the removal of adsorbed intermediates at lower potential with the addition of Cu and Ir.

  6. Ni catalyst wash-coated on metal monolith with enhanced heat-transfer capability for steam reforming

    NASA Astrophysics Data System (ADS)

    Ryu, Jae-Hong; Lee, Kwan-Young; La, Howon; Kim, Hak-Joo; Yang, Jung-Il; Jung, Heon

    A commercial Ni-based catalyst is wash-coated on a monolith made of 50 μm-thick fecralloy plates. Compared with the same volume of coarsely powdered Ni catalysts, the monolith wash-coated Ni catalysts give higher methane conversion in the steam reforming reaction, especially at gas hourly space velocities (GHSV) higher than 28,000 h -1, and with no pressure drop. A higher conversion of the monolith catalyst is obtained, even though it contains a lower amount of active catalyst (3 g versus 17 g for a powdered catalyst), which indicates that the heat-transfer capability of the wash-coated Ni catalyst is significantly enhanced by the use of a metal monolith. The efficacy of the monolith catalyst is tested using a shell-and-tube type heat-exchanger reactor with 912 cm 3 of the monolith catalyst charged on to the tube side and hot combusted gas supplied to the shell side in a counter-current direction to the reactant flow. A methane conversion greater than 94% is obtained at a GHSV of 7300 h -1 and an average temperature of 640 °C. Nickel catalysts should first be reduced to become active for steam reforming. Doping a small amount (0.12 wt.%) of noble metal (Ru or Pt) in the commercial Ni catalyst renders the wash-coated catalyst as active as a pre-reduced Ni catalyst. Thus, noble metal-doped Ni appears useful for steam reforming without any pre-reduction procedure.

  7. Enhanced Photochemical Hydrogen Production by a Molecular Diiron Catalyst Incorporated into a Metal-Organic Framework

    SciTech Connect

    Pullen, Sonja; Fei, Honghan; Orthaber, Andreas; Cohen, Seth M.; Ott, Sascha

    2013-12-04

    A molecular proton reduction catalyst [FeFe](dcbdt)(CO)6 (1, dcbdt = 1,4-dicarboxylbenzene-2,3-dithiolate) with structural similarities to [FeFe]-hydrogenase active sites has been incorporated into a highly robust Zr(IV)-based metal–organic framework (MOF) by postsynthetic exchange (PSE). The PSE protocol is crucial as direct solvothermal synthesis fails to produce the functionalized MOF. The molecular integrity of the organometallic site within the MOF is demonstrated by a variety of techniques, including X-ray absorption spectroscopy. In conjunction with [Ru(bpy)3]2+ as a photosensitizer and ascorbate as an electron donor, MOF-[FeFe](dcbdt)(CO)6 catalyzes photochemical hydrogen evolution in water at pH 5. The immobilized catalyst shows substantially improved initial rates and overall hydrogen production when compared to a reference system of complex 1 in solution. Improved catalytic performance is ascribed to structural stabilization of the complex when incorporated in the MOF as well as the protection of reduced catalysts 1 and 12– from undesirable charge recombination with oxidized ascorbate.

  8. Enhanced photochemical hydrogen production by a molecular diiron catalyst incorporated into a metal-organic framework.

    PubMed

    Pullen, Sonja; Fei, Honghan; Orthaber, Andreas; Cohen, Seth M; Ott, Sascha

    2013-11-13

    A molecular proton reduction catalyst [FeFe](dcbdt)(CO)6 (1, dcbdt = 1,4-dicarboxylbenzene-2,3-dithiolate) with structural similarities to [FeFe]-hydrogenase active sites has been incorporated into a highly robust Zr(IV)-based metal-organic framework (MOF) by postsynthetic exchange (PSE). The PSE protocol is crucial as direct solvothermal synthesis fails to produce the functionalized MOF. The molecular integrity of the organometallic site within the MOF is demonstrated by a variety of techniques, including X-ray absorption spectroscopy. In conjunction with [Ru(bpy)3](2+) as a photosensitizer and ascorbate as an electron donor, MOF-[FeFe](dcbdt)(CO)6 catalyzes photochemical hydrogen evolution in water at pH 5. The immobilized catalyst shows substantially improved initial rates and overall hydrogen production when compared to a reference system of complex 1 in solution. Improved catalytic performance is ascribed to structural stabilization of the complex when incorporated in the MOF as well as the protection of reduced catalysts 1(-) and 1(2-) from undesirable charge recombination with oxidized ascorbate.

  9. Enhanced MEA Performance for PEMFCs under Low Relative Humidity and Low Oxygen Content Conditions via Catalyst Functionalization

    SciTech Connect

    Xin, Le; Yang, Fan; Xie, Jian; Yang, Zhiwei; Kariuki, Nancy N.; Myers, Deborah J.; Peng, Jui-Kun; Wang, Xiaohua; Ahluwalia, Rajesh K.; Yu, Kang; Ferreira, Paulo J.; Bonastre, Alex Martinez; Fongalland, Dash; Sharman, Jonathan

    2017-01-01

    This work demonstrates that functionalizing annealed-Pt/Ketjen black EC300j (a-Pt/KB) and dealloyed-PtNi/Ketjen black EC300j (d-PtNi/KB) catalysts using p-phenyl sulfonic acid can effectively enhance performance in the membrane electrode assemblies (MEAs) of proton exchange membrane fuel cells (PEMFCs). The functionalization increased the size of both Pt and PtNi catalyst particles and resulted in the further leaching of Ni from the PtNi catalyst while promoting the formation of nanoporous PtNi nanoparticles. The size of the SO3H-Pt/KB and SO3H-PtNi/KB carbon-based aggregates decreased dramatically, leading to the formation of catalyst layers with narrower pore size distributions.MEA tests highlighted the benefits of the surface functionalization, in which the cells with SO3H-Pt/KB and SO3H-PtNi/KB cathode catalysts showed superior high current density performance under reduced RH conditions, in comparison with cells containing annealed Pt/KB (a-Pt/KB) and de-alloyed PtNi/KB (d-PtNi/KB) catalysts. The performance improvement was particularly evident when using reactant gases with low relative humidity, indicating that the hydrophilic functional groups on the carbon improved the water retention in the cathode catalyst layer. These results show a new avenue for enhancing catalyst performance for the next generation of catalytic materials for PEMFCs.

  10. Enhanced protection of PDMS-embedded palladium catalysts by co-embedding of sulphide-scavengers.

    PubMed

    Comandella, Daniele; Ahn, Min Hyung; Kim, Hojeong; Mackenzie, Katrin

    2017-12-01

    For Pd-containing hydrodechlorination catalysts, coating with poly(dimethyl siloxane) (PDMS) was proposed earlier as promising protection scheme against poisoning. The PDMS coating can effectively repel non-permeating poisons (such as SO3(2-)) retaining the hydrodechlorination Pd activity. In the present study, the previously achieved protection efficiency was enhanced by incorporation of sulphide scavengers into the polymer. The embedded scavengers were able to bind permeating non-ionic poisons (such as H2S) during their passage through PDMS prior to Pd contact which ensured an extended catalyst lifetime. Three scavenger types forming non-permeable sulphur species from H2S - alkaline, oxidative or iron-based compounds - were either incorporated into single-layer coats around individual Pd/Al2O3 particles or into a second layer above Pd-containing PDMS films (Pd-PDMS). Hydrodechlorination and hydrogenation were chosen as model reactions, carried out in batch and continuous-flow reactors. Batch tests with all scavenger-containing catalysts showed extended Pd protection compared to scavenger-free catalysts. Solid alkaline compounds (Ca(OH)2, NaOH, CaO) and MnO2 showed the highest instantaneous scavenger efficiencies (retained Pd activity=30-60%), while iron-based catalysts, such as nano zero-valent iron (nZVI) or ferrocene (FeCp2), proved less efficient (1-10%). When stepwise poisoning was applied, the protection efficiency of iron-based and oxidizing compounds was higher in the long term than that of alkaline solids. Long-term experiments in mixed-flow reactors were performed with selected scavengers, revealing the following trend of protection efficiency: CaO2>Ca(OH)2>FeCp2. Under field-simulating conditions using a fixed-bed reactor, the combination of sulphide pre-oxidation in the water phase by H2O2 and local scavenger-enhanced Pd protection was successful. The oxidizing agent H2O2 does not disturb the Pd-catalysed reduction, while the PDMS

  11. CeO2-based catalysts with engineered morphologies for soot oxidation to enhance soot-catalyst contact.

    PubMed

    Miceli, Paolo; Bensaid, Samir; Russo, Nunzio; Fino, Debora

    2014-01-01

    AS MORPHOLOGY PLAYS A RELEVANT ROLE IN SOLID/SOLID CATALYSIS, WHERE THE NUMBER OF CONTACT POINTS IS A CRITICAL FEATURE IN THIS KIND OF REACTION, THREE DIFFERENT CERIA MORPHOLOGIES HAVE BEEN INVESTIGATED IN THIS WORK AS SOOT OXIDATION CATALYSTS: ceria nanofibers, which can become organized as a catalytic network inside diesel particulate filter channels and thus trap soot particles at several contact points but have a very low specific surface area (4 m(2)/g); solution combustion synthesis ceria, which has an uncontrolled morphology but a specific surface area of 31 m(2)/g; and three-dimensional self-assembled (SA) ceria stars, which have both high specific surface area (105 m(2)/g) and a high availability of contact points. A high microporous volume of 0.03 cm(3)/g and a finer crystallite size compared to the other morphologies suggested that self-assembled stars could improve their redox cycling capability and their soot oxidation properties. In this comparison, self-assembled stars have shown the best tendency towards soot oxidation, and the temperature of non-catalytic soot oxidation has dropped from 614°C to 403°C in tight and to 552°C in loose contact conditions, respectively. As far as the loose contact results are concerned, this condition being the most realistic and hence the most significant, self-assembled stars have exhibited the lowest T 10% onset temperature of this trio (even after ageing), thus proving their higher intrinsic activity. Furthermore, the three-dimensional shape of self-assembled stars may involve more of the soot cake layer than the solution combustion synthesis or nanofibers of ceria and thus enhance the total number of contact points. The results obtained through this work have encouraged our efforts to understand soot oxidation and to transpose these results to real diesel particulate filters.

  12. CeO2-based catalysts with engineered morphologies for soot oxidation to enhance soot-catalyst contact

    PubMed Central

    2014-01-01

    As morphology plays a relevant role in solid/solid catalysis, where the number of contact points is a critical feature in this kind of reaction, three different ceria morphologies have been investigated in this work as soot oxidation catalysts: ceria nanofibers, which can become organized as a catalytic network inside diesel particulate filter channels and thus trap soot particles at several contact points but have a very low specific surface area (4 m2/g); solution combustion synthesis ceria, which has an uncontrolled morphology but a specific surface area of 31 m2/g; and three-dimensional self-assembled (SA) ceria stars, which have both high specific surface area (105 m2/g) and a high availability of contact points. A high microporous volume of 0.03 cm3/g and a finer crystallite size compared to the other morphologies suggested that self-assembled stars could improve their redox cycling capability and their soot oxidation properties. In this comparison, self-assembled stars have shown the best tendency towards soot oxidation, and the temperature of non-catalytic soot oxidation has dropped from 614°C to 403°C in tight and to 552°C in loose contact conditions, respectively. As far as the loose contact results are concerned, this condition being the most realistic and hence the most significant, self-assembled stars have exhibited the lowest T10% onset temperature of this trio (even after ageing), thus proving their higher intrinsic activity. Furthermore, the three-dimensional shape of self-assembled stars may involve more of the soot cake layer than the solution combustion synthesis or nanofibers of ceria and thus enhance the total number of contact points. The results obtained through this work have encouraged our efforts to understand soot oxidation and to transpose these results to real diesel particulate filters. PMID:24940178

  13. Photochemically enhanced degradation of phenol using heterogeneous Fenton-type catalysts.

    PubMed

    He, Feng; Shen, Xue-You; Lei, Le-Cheng

    2003-05-01

    The degradation of phenol was carried out using heterogeneous Fenton-type catalysts in the presence of H2O2 and UV. Catalysts were prepared by exchanging and immobilizing Fe2+ in zeolite 13X, silica gel or Al2O3. The concentration of phenol solution was 100 mg/L. The amount of H2O2 added was the stoichiometric amount of H2O2 required for the total oxidation of phenol. Under the irradiation of medium pressure light (300 W) phenol was mineralized within 1 h in the presence of Fe2+/zeolite 13X. The COD removal rate was enhanced in the presence of Fe2+/zeolite 13X compared to that of Fe2+/silica gel or Fe2+/Al2O3. Analogous homogenous photo-Fenton reaction with equivalent Fe2+ was also carried out to evaluate the catalysis efficiency of Fe2+/zeolite 13X. Results showed that the COD removal rate was near to that of homogeneous Fenton, while heterogeneous Fe2+/zeolite 13X catalyst could be recycled.

  14. Plasmon-enhanced reverse water gas shift reaction over oxide supported Au catalysts

    SciTech Connect

    Upadhye, AA; Ro, I; Zeng, X; Kim, HJ; Tejedor, I; Anderson, MA; Dumesic, JA; Huber, GW

    2015-01-01

    We show that localized surface plasmon resonance (LSPR) can enhance the catalytic activities of different oxide-supported Au catalysts for the reverse water gas shift (RWGS) reaction. Oxide-supported Au catalysts showed 30 to 1300% higher activity for RWGS under visible light compared to dark conditions. Au/TiO2 catalyst prepared by the deposition-precipitation (DP) method with 3.5 nm average Au particle size showed the highest activity for the RWGS reaction. Visible light is converted into chemical energy for this reaction with up to a 5% overall efficiency. A shift in the apparent activation energy (from 47 kJ mol(-1) in dark to 35 kJ mol(-1) in light) and apparent reaction order with respect to CO2 (from 0.5 in dark to 1.0 in light) occurs due to the LSPR. Our kinetic results indicate that the LSPR increases the rate of either the hydroxyl hydrogenation or carboxyl decomposition more than any other steps in the reaction network.

  15. Nanostructured polyaniline-decorated Pt/C@PANI core-shell catalyst with enhanced durability and activity.

    PubMed

    Chen, Siguo; Wei, Zidong; Qi, XueQiang; Dong, Lichun; Guo, Yu-Guo; Wan, Lijun; Shao, Zhigang; Li, Li

    2012-08-15

    We have designed and synthesized a polyaniline (PANI)-decorated Pt/C@PANI core-shell catalyst that shows enhanced catalyst activity and durability compared with nondecorated Pt/C. The experimental results demonstrate that the activity for the oxygen reduction reaction strongly depends on the thickness of the PANI shell and that the greatest enhancement in catalytic properties occurs at a thickness of 5 nm, followed by 2.5, 0, and 14 nm. Pt/C@PANI also demonstrates significantly improved stability compared with that of the unmodified Pt/C catalyst. The high activity and stability of the Pt/C@PANI catalyst is ascribed to its novel PANI-decorated core-shell structure, which induces both electron delocalization between the Pt d orbitals and the PANI π-conjugated ligand and electron transfer from Pt to PANI. The stable PANI shell also protects the carbon support from direct exposure to the corrosive environment.

  16. Enhancing the stability of copper chromite catalysts for the selective hydrogenation of furfural using ALD overcoating

    SciTech Connect

    Zhang, Hongbo; Lei, Yu; Kropf, A. Jeremy; Zhang, Guanghui; Elam, Jeffrey W.; Miller, Jeffrey T.; Sollberger, Fred; Ribeiro, Fabio; Akatay, Cem M.; Stach, Eric A.; Dumesic, James A; Marshall, Christopher L.

    2014-08-01

    The stability of a gas-phase furfural hydrogenation catalyst (CuCr2O4 center dot CuO) was enhanced by depositing a thin Al2O3 layer using atomic layer deposition (ALD). Based on temperature-programed reduction (TPR) measurements, the reduction temperature of Cu was raised significantly, and the activation energy for furfural reduction was decreased following the ALD treatment. Thinner ALD layers yielded higher furfural hydrogenation activities. X-ray absorption fine structure (XAFS) spectroscopy studies indicated that Cu1+/Cu-0 are the active species for furfural reduction.

  17. First principles study of doped carbon supports for enhanced platinum catalysts.

    PubMed

    Holme, Timothy; Zhou, Yingke; Pasquarelli, Robert; O'Hayre, Ryan

    2010-08-28

    Highly oriented pyrolytic graphite (HOPG) implanted with N, Ar and B is studied as a support for platinum nanoparticle catalysts for fuel cells. Experimentally, we find that Pt supported by N-HOPG is more disperse, more catalytically active and suffers less particle ripening than native HOPG, while Pt supported on Ar-irradiated HOPG is slightly more active but ripens more than Pt on native HOPG. Defective HOPG supports are modeled by density functional theory (DFT) calculations that confirm and explain the above experimental results. First, defect energetics are studied to demonstrate that nitrogen doping at high doses likely causes agglomerated nitrogenous defect clusters, and irradiation with Ar ions creates vacancies that agglomerate in vacancy clusters. Second, Pt catalyst particle nucleation and agglomeration is studied. For Pt clusters supported on HOPG with nitrogen defects, calculations show a greater driving force for nucleation and greater particle tethering. For Pt clusters supported on HOPG with vacancy aggregations, this study shows a strong driving force for nucleation and a much enhanced tendency for particle ripening. Third, the electronic structure of Pt clusters on different supports is calculated. Finally, reaction energetics are calculated for two likely reaction pathways over Pt clusters supported on different HOPG substrates. Pt-N-HOPG shows modified electronic structure of the Pt catalyst and increased activity towards oxygen. Pt-Ar-HOPG shows slightly enhanced catalytic activity towards oxygen. In all respects, the findings agree with experiment. The calculations attribute the catalytic activity changes primarily to changes in the workfunction and secondarily to the d-band structure of supported Pt particles.

  18. Enhanced esterification of oleic acid and methanol by deep eutectic solvent assisted Amberlyst heterogeneous catalyst.

    PubMed

    Pan, Ying; Alam, Md Asraful; Wang, Zhongming; Wu, Jingcheng; Zhang, Yi; Yuan, Zhenhong

    2016-11-01

    In present study, esterification of oleic acid with methanol using deep eutectic solvent (DES) assisted Amberlyst heterogeneous catalyst was investigated to produce biodiesel. Results showed that esterification efficiency was enhanced by the DES. The combined effect of DES on Amberlyst BD20 (BD20) is better than Amberlyst 15 (A-15) due to different structure. The optimal reaction conditions were 12:1M ratio of methanol to oleic acid, 20%(wt/wt) catalyst (BD20-DES (2:8) and A-15-DES (8:2)) at 85°C for 100min with agitating at 200rpm. The mechanism involved in catalysis and their capacity to reuse were studied. We proposed, Choline chloride-glycerol (Chcl-gly) DES could enhance the Amberlyst function due to the hydrogen bond effect on both DES and water. BD20 has fewer pores than A-15, have desirable performance in decreasing the inhibition the water during esterification of high FFA content and provide better performance in reuse.

  19. Enhanced stability of multilayer graphene-supported catalysts for polymer electrolyte membrane fuel cell cathodes

    NASA Astrophysics Data System (ADS)

    Marinkas, A.; Hempelmann, R.; Heinzel, A.; Peinecke, V.; Radev, I.; Natter, H.

    2015-11-01

    One of the biggest challenges in the field of polymer electrolyte membrane fuel cells (PEMFC) is to enhance the lifetime and the long-term stability of PEMFC electrodes, especially of cathodes, furthermore, to reduce their platinum loading, which could lead to a cost reduction for efficient PEMFCs. These demands could be achieved with a new catalyst support architecture consisting of a composite of carbon structures with significant different morphologies. A highly porous cathode catalyst support layer is prepared by addition of various carbon types (carbon black particles, multi-walled carbon nanotubes (MWCNT)) to multilayer graphene (MLG). The reported optimized cathodes shows extremely high durability and similar performance to commercial standard cathodes but with 89% lower Pt loading. The accelerated aging protocol (AAP) on the membrane electrode assemblies (MEA) shows that the presence of MLG increases drastically the durability and the Pt-extended electrochemical surface area (ECSA). In fact, after the AAP slightly enhanced performance can be observed for the MLG-containing cathodes instead of a performance loss, which is typical for the commercial carbon-based cathodes. Furthermore, the presence of MLG drastically decreases the ECSA loss rate. The MLG-containing cathodes show up to 6.8 times higher mass-normalized Pt-extended ECSA compared to the commercial standard systems.

  20. Analysis of Oxidation State of Multilayered Catalyst Thin Films for Carbon Nanotube Growth Using Plasma-Enhanced Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Okita, Atsushi; Ozeki, Atsushi; Suda, Yoshiyuki; Nakamura, Junji; Oda, Akinori; Bhattacharyya, Krishnendu; Sugawara, Hirotake; Sakai, Yosuke

    2006-10-01

    We synthesized vertically aligned carbon nanotubes (CNTs) using multilayered catalyst thin films (Fe/Al2O3 and Al2O3/Fe/Al2O3) by RF (13.56 MHz) CH4/H2/Ar plasma-enhanced chemical vapor deposition. Pretreatment of the catalyst is crucial for CNT growth. In this paper, we analyzed the effect of catalyst reduction on CNT growth. Catalyst thin films on substrates were reduced by H2 plasma pretreatment at 550 °C to form nanometer-sized catalyst particles. The multilayered thin films were analyzed; the chemical composition and oxidation state by X-ray photoelectron spectroscopy (XPS) and the surface morphology by scanning electron microscopy (SEM). The Fe 2p peak of the XPS spectra showed that FexOy in the as-deposited catalyst was effectively reduced to Fe by a pretreatment of duration 4 min. Using this catalyst, we obtained CNTs with an average diameter of 10.7 nm and an average length of 5.3 μm. However, pretreatment longer than 4 min resulted in shorter CNTs and the Fe peak was shifted from Fe to Fe3O4. These transitions (Fe2O3→Fe3O4→Fe→Fe3O4) can be explained by the enthalpy of the oxides. This result indicates the presence of an optimum ratio between Fe and FexOy to maximize the CNT lengths.

  1. In Situ Self-Sacrificed Template Synthesis of Fe-N/G Catalysts for Enhanced Oxygen Reduction.

    PubMed

    Lai, Qingxue; Su, Qi; Gao, Qingwen; Liang, Yanyu; Wang, Yuxi; Yang, Zhi; Zhang, Xiaogang; He, Jianping; Tong, Hao

    2015-08-19

    To facilely prepare high-performance Fe-N/G oxygen reduction catalysts via a simple and controllable route from available and low-cost materials is still a challenge. Herein, we develop an in situ self-sacrificed template strategy to synthesize Fe-N/G catalysts from melamine, glucose, and FeSO4·7H2O. Fe/Fe3C@graphitic carbon nanocapsules are uniformly formed on the NG surface to create a highly opened and stable mesoporous framework structure. Furthermore, effectively doped N sites and high active Fe-Nx sites are synchronously constructed on such structures, leading to an enhanced synergistic effect for ORR and promising the Fe-N/G catalyst a similar catalytic activity and four-electron selectivity, but superior stability to commercial 30 wt % Pt/C catalysts in 0.1 M KOH solution under the same loading.

  2. Enhanced low-temperature NH3-SCR performance of MnOx/CeO2 catalysts by optimal solvent effect

    NASA Astrophysics Data System (ADS)

    Yao, Xiaojiang; Kong, Tingting; Chen, Li; Ding, Shimin; Yang, Fumo; Dong, Lin

    2017-10-01

    A series of MnOx/CeO2 catalysts were prepared by modulating the solvents (deionized water (DW), anhydrous ethanol (AE), acetic acid (AA), and oxalic acid (OA) solution) with the purpose of improving the low-temperature NH3-SCR performance, broadening the operating temperature window, and enhancing the H2O + SO2 resistance. The synthesized catalysts were characterized by means of N2-physisorption, XRD, EDS mapping, Raman, XPS, H2-TPR, NH3-TPD, and in situ DRIFTS technologies. Furthermore, the catalytic performance and H2O + SO2 resistance were evaluated by NH3-SCR model reaction. The obtained results indicate that MnOx/CeO2 catalyst prepared with oxalic acid solution as a solvent exhibits the best catalytic performance among these catalysts, which shows above 80% NO conversion during a wide operating temperature range of 100-250 °C and good H2O + SO2 resistance for low-temperature NH3-SCR reaction. This is related to that oxalic acid solution can promote the dispersion of MnOx and enhance the electron interaction between MnOx and CeO2, which are beneficial to improving the physicochemical property of MnOx/CeO2 catalyst, and further lead to the enhancement of catalytic performance and good H2O + SO2 resistance.

  3. Iron-based cathode catalyst with enhanced power density in polymer electrolyte membrane fuel cells.

    PubMed

    Proietti, Eric; Jaouen, Frédéric; Lefèvre, Michel; Larouche, Nicholas; Tian, Juan; Herranz, Juan; Dodelet, Jean-Pol

    2011-08-02

    H(2)-air polymer-electrolyte-membrane fuel cells are electrochemical power generators with potential vehicle propulsion applications. To help reduce their cost and encourage widespread use, research has focused on replacing the expensive Pt-based electrocatalysts in polymer-electrolyte-membrane fuel cells with a lower-cost alternative. Fe-based cathode catalysts are promising contenders, but their power density has been low compared with Pt-based cathodes, largely due to poor mass-transport properties. Here we report an iron-acetate/phenanthroline/zeolitic-imidazolate-framework-derived electrocatalyst with increased volumetric activity and enhanced mass-transport properties. The zeolitic-imidazolate-framework serves as a microporous host for phenanthroline and ferrous acetate to form a catalyst precursor that is subsequently heat treated. A cathode made with the best electrocatalyst from this work, tested in H(2)-O(2,) has a power density of 0.75 W cm(-2) at 0.6 V, a meaningful voltage for polymer-electrolyte-membrane fuel cells operation, comparable with that of a commercial Pt-based cathode tested under identical conditions.

  4. Enhanced carbon tolerance on Ni-based reforming catalyst with Ir alloying: A DFT study

    NASA Astrophysics Data System (ADS)

    Ahn, Kiyong; Choi, Sungjun; Lee, Jong-Ho; Kim, Byung-Kook; Kim, Jedo; Kim, Hyoungchul

    2017-10-01

    Carbon deposition is a major cause of performance degradation for the Ni-based catalyst used in steam reforming of hydrocarbons. In this work, we perform first principle calculations to show that carbon tolerance behavior can be significantly enhanced by alloying Ni with Ir. The most stable atomic structure predicted by the surface phased diagram shows that Ir atoms prefer to stay on the surface of the alloy ensuring their exposure to the incoming gas. We find that the presence of Ir atoms suppress the surface migration of carbon atoms and weaken the stability of the adsorbed carbon agglomerates. Finally, we elucidate that the local reactivity change caused by the shift in the d-band structure is responsible for such good carbon tolerance behavior.

  5. Facile one-pot synthesis of Pt/graphene-TiO2 hybrid catalyst with enhanced methanol electrooxidation performance

    NASA Astrophysics Data System (ADS)

    Zhao, Lei; Wang, Zhen-Bo; Liu, Jing; Zhang, Jing-Jia; Sui, Xu-Lei; Zhang, Li-Mei; Gu, Da-Ming

    2015-04-01

    Pt/graphene-TiO2 hybrid catalysts have been synthesized by a facile one-pot solvothermal method. The Structural properties of obtained Pt/graphene-TiO2 catalysts are characterized by X-ray diffraction (XRD), Energy dispersive analysis of X-ray (EDAX) and transmission electron microscopy (TEM).Interesting, TEM presents Pt nanoparticles seem preferentially to locate between TiO2 and graphene, forming the unique triple junctions structure. The electrochemical experimental results indicate that Pt/graphene-TiO2 catalyst exhibits 1.46 times higher activity for methanol electrooxidation than that of Pt/graphene and its stability is improved by 15% as compared with Pt/graphene. Moreover, performance of Pt/graphene-TiO2 hybrid catalyst is evaluated by the Single Fuel Cell Tests for the first time. Single fuel cell tests show the maximum power density of the direct methanol fuel cell using Pt/graphene-TiO2 as the anode catalyst is increased by 55% compared with that using Pt/graphene catalyst at the same operating conditions. The significantly enhanced electrochemical performance can be ascribed to (1) the synergetic effect between Pt, graphene and TiO2; (2) strong metal-support interaction (SMSI) between Pt nanoparticles and TiO2. These findings suggest their great potential applications in fuel cells.

  6. Enhanced methanol electro-oxidation reaction on Pt-CoOx/MWCNTs hybrid electro-catalyst

    NASA Astrophysics Data System (ADS)

    Nouralishahi, Amideddin; Rashidi, Ali Morad; Mortazavi, Yadollah; Khodadadi, Abbas Ali; Choolaei, Mohammadmehdi

    2015-04-01

    The electro-catalytic behavior of Pt-CoOx/MWCNTs in methanol electro-oxidation reaction (MOR) is investigated and compared to that of Pt/MWCNTs. The electro-catalysts were synthesized by an impregnation method using NaBH4 as the reducing agent. The morphological and physical characteristics of samples are examined by XRD, TEM, ICP and EDS techniques. In the presence of CoOx, Pt nanoparticles were highly distributed on the support with an average particle size of 2 nm, an obvious decrease from 5.1 nm for Pt/MWCNTs. Cyclic voltammetry, CO-stripping, Chronoamperometry, and electrochemical impedance spectroscopy (EIS) measurements are used to study the electrochemical behavior of the electro-catalysts. The results revealed a considerable enhancement in the oxidation kinetics of COads on Pt active sites by the participation of CoOx. Compared to Pt/MWCNTs, Pt-CoOx/MWCNTs sample has a larger electrochemical active surface area (ECSA) and higher electro-catalytic activity and stability toward methanol electro-oxidation. According to the results of cyclic voltammetry, the forward anodic peak current density enhances more than 89% at the optimum atomic ratio of Pt:Co = 2:1. Furthermore, inclusion of cobalt oxide species causes the onset potential of methanol electro-oxidation reaction to shift 84 mV to negative values compared to that on Pt/MWCNTs. Based on EIS data, dehydrogenation of methanol is the rate-determining step of MOR on both Pt/MWCNTs and Pt-CoOx/MWCNTs, at small overpotentials. However, at higher overpotentials, the oxidation of adsorbed oxygen-containing groups controls the total rate of MOR process.

  7. Radiofrequency treatment enhances the catalytic function of an immobilized nanobiohybrid catalyst.

    PubMed

    San, Boi Hoa; Ha, Eun-Ju; Paik, Hyun-Jong; Kim, Kyeong Kyu

    2014-06-07

    Biocatalysis, the use of enzymes in chemical transformation, has undergone intensive development for a wide range of applications. As such, maximizing the functionality of enzymes for biocatalysis is a major priority to enable industrial use. To date, many innovative technologies have been developed to address the future demand of enzymes for these purposes, but maximizing the catalytic activity of enzymes remains a challenge. In this study, we demonstrated that the functionality of a nanobiocatalyst could be enhanced by combining immobilization and radiofrequency (RF) treatment. Aminopeptidase PepA-encapsulating 2 nm platinum nanoparticles (PepA-PtNPs) with the catalytic activities of hydrolysis and hydrogenation were employed as multifunctional nanobiocatalysts. Immobilizing the nanobiocatalysts in a hydrogel using metal chelation significantly enhanced their functionalities, including catalytic power, thermal-stability, pH tolerance, organic solvent tolerance, and reusability. Most importantly, RF treatment of the hydrogel-immobilized PepA-PtNPs increased their catalytic power by 2.5 fold greater than the immobilized PepA. Our findings indicate that the catalytic activities and functionalities of PepA-PtNPs are greatly enhanced by the combination of hydrogel-immobilization and RF treatment. Based on our findings, we propose that RF treatment of nanobiohybrid catalysts immobilized on the bulk hydrogel represents a new strategy for achieving efficient biocatalysis.

  8. Pd@Pt core-shell concave decahedra: A class of catalysts for the oxygen reduction reaction with enhanced activity and durability

    DOE PAGES

    Wang, Xue; Vera, Madeline; Chi, Miaofang; ...

    2015-11-13

    Here, we report a facile synthesis of multiply twinned Pd@Pt core shell concave decahedra by controlling the deposition of Pt on preformed Pd decahedral seeds. The Pt atoms are initially deposited on the vertices of a decahedral seed, followed by surface diffusion to other regions along the edges/ridges and then across the faces. Different from the coating of a Pd icosahedral seed, the Pt atoms prefer to stay at the vertices and edges/ridges of a decahedral seed even when the deposition is conducted at 200 degrees C, naturally generating a core shell structure covered by concave facets. The nonuniformity inmore » the Pt coating can be attributed to the presence of twin boundaries at the vertices, as well as the {100} facets and twin defects along the edges/ridges of a decahedron, effectively trapping the Pt adatoms at these high-energy sites. As compared to a commercial Pt/C catalyst, the Pd@Pt concave decahedra show substantial enhancement in both catalytic activity and durability toward the oxygen reduction reaction (ORR). For the concave decahedra with 29.6% Pt by weight, their specific (1.66 mA/cm2pt) and mass (1.60 A/mg/2pt) ORR activities are enhanced by 4.4 and 6.6 times relative to those of the Pt/C catalyst (0.36 mA/cm2pt and 0.32 A/mgpt, respectively). After 10 000 cycles of accelerated durability test, the concave decahedra still exhibit a mass activity of 0.69 A/mgpt, more than twice that of the pristine Pt/C catalyst.« less

  9. Pd@Pt core-shell concave decahedra: A class of catalysts for the oxygen reduction reaction with enhanced activity and durability

    SciTech Connect

    Wang, Xue; Vera, Madeline; Chi, Miaofang; Xia, Younan; Luo, Ming; Huang, Hongwen; Ruditskiy, Aleksey; Park, Jinho; Bao, Shixiong; Liu, Jingyue; Howe, Jane; Xie, Zhaoxiong

    2015-11-13

    Here, we report a facile synthesis of multiply twinned Pd@Pt core shell concave decahedra by controlling the deposition of Pt on preformed Pd decahedral seeds. The Pt atoms are initially deposited on the vertices of a decahedral seed, followed by surface diffusion to other regions along the edges/ridges and then across the faces. Different from the coating of a Pd icosahedral seed, the Pt atoms prefer to stay at the vertices and edges/ridges of a decahedral seed even when the deposition is conducted at 200 degrees C, naturally generating a core shell structure covered by concave facets. The nonuniformity in the Pt coating can be attributed to the presence of twin boundaries at the vertices, as well as the {100} facets and twin defects along the edges/ridges of a decahedron, effectively trapping the Pt adatoms at these high-energy sites. As compared to a commercial Pt/C catalyst, the Pd@Pt concave decahedra show substantial enhancement in both catalytic activity and durability toward the oxygen reduction reaction (ORR). For the concave decahedra with 29.6% Pt by weight, their specific (1.66 mA/cm2pt) and mass (1.60 A/mg/2pt) ORR activities are enhanced by 4.4 and 6.6 times relative to those of the Pt/C catalyst (0.36 mA/cm2pt and 0.32 A/mgpt, respectively). After 10 000 cycles of accelerated durability test, the concave decahedra still exhibit a mass activity of 0.69 A/mgpt, more than twice that of the pristine Pt/C catalyst.

  10. Pd@Pt Core-Shell Concave Decahedra: A Class of Catalysts for the Oxygen Reduction Reaction with Enhanced Activity and Durability.

    PubMed

    Wang, Xue; Vara, Madeline; Luo, Ming; Huang, Hongwen; Ruditskiy, Aleksey; Park, Jinho; Bao, Shixiong; Liu, Jingyue; Howe, Jane; Chi, Miaofang; Xie, Zhaoxiong; Xia, Younan

    2015-12-02

    We report a facile synthesis of multiply twinned Pd@Pt core-shell concave decahedra by controlling the deposition of Pt on preformed Pd decahedral seeds. The Pt atoms are initially deposited on the vertices of a decahedral seed, followed by surface diffusion to other regions along the edges/ridges and then across the faces. Different from the coating of a Pd icosahedral seed, the Pt atoms prefer to stay at the vertices and edges/ridges of a decahedral seed even when the deposition is conducted at 200 °C, naturally generating a core-shell structure covered by concave facets. The nonuniformity in the Pt coating can be attributed to the presence of twin boundaries at the vertices, as well as the {100} facets and twin defects along the edges/ridges of a decahedron, effectively trapping the Pt adatoms at these high-energy sites. As compared to a commercial Pt/C catalyst, the Pd@Pt concave decahedra show substantial enhancement in both catalytic activity and durability toward the oxygen reduction reaction (ORR). For the concave decahedra with 29.6% Pt by weight, their specific (1.66 mA/cm(2)Pt) and mass (1.60 A/mgPt) ORR activities are enhanced by 4.4 and 6.6 times relative to those of the Pt/C catalyst (0.36 mA/cm(2)Pt and 0.32 A/mgPt, respectively). After 10,000 cycles of accelerated durability test, the concave decahedra still exhibit a mass activity of 0.69 A/mgPt, more than twice that of the pristine Pt/C catalyst.

  11. Beneficial Role of Copper in the Enhancement of Durability of Ordered Intermetallic PtFeCu Catalyst for Electrocatalytic Oxygen Reduction.

    PubMed

    Arumugam, Balamurugan; Tamaki, Takanori; Yamaguchi, Takeo

    2015-08-05

    Design of Pt alloy catalysts with enhanced activity and durability is a key challenge for polymer electrolyte membrane fuel cells. In the present work, we compare the durability of the ordered intermetallic face-centered tetragonal (fct) PtFeCu catalyst for the oxygen reduction reaction (ORR) relative to its counterpart bimetallic catalysts, i.e., the ordered intermetallic fct-PtFe catalyst and the commercial catalyst from Tanaka Kikinzoku Kogyo, TKK-PtC. Although both fct catalysts initially exhibited an ordered structure and mass activity approximately 2.5 times higher than that of TKK-Pt/C, the presence of Cu at the ordered intermetallic fct-PtFeCu catalyst led to a significant enhancement in durability compared to that of the ordered intermetallic fct-PtFe catalyst. The ordered intermetallic fct-PtFeCu catalyst retained more than 70% of its mass activity and electrochemically active surface area (ECSA) over 10 000 durability cycles carried out at 60 °C. In contrast, the ordered intermetallic fct-PtFe catalyst maintained only about 40% of its activity. The temperature of the durability experiment is also shown to be important: the catalyst was more severely degraded at 60 °C than at room temperature. To obtain insight into the observed enhancement in durability of fct-PtFeCu catalyst, a postmortem analysis of the ordered intermetallic fct-PtFeCu catalyst was carried out using scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDX) line scan. The STEM-EDX line scans of the ordered intermetallic fct-PtFeCu catalyst over 10 000 durability cycles showed a smaller degree of Fe and Cu dissolution from the catalyst. Conversely, large dissolution of Fe was identified in the ordered intermetallic fct-PtFe catalyst, indicating a lesser retention of Fe that causes the destruction of ordered structure and gives rise to poor durability. The enhancement in the durability of the ordered intermetallic fct-PtFeCu catalyst is ascribed to

  12. Ultrasonic enhance acid hydrolysis selectivity of cellulose with HCl-FeCl3 as catalyst.

    PubMed

    Li, Jinbao; Zhang, Xiangrong; Zhang, Meiyun; Xiu, Huijuan; He, Hang

    2015-03-06

    The effect of ultrasonic pretreatment coupled with HCl-FeCl3 catalyst was evaluated to hydrolyze cellulose amorphous regions. The ultrasonic pretreatment leads to cavitation that affects the morphology and microstructure of fibers, enhancing the accessibility of chemical reagent to the loosened amorphous regions of cellulose. In this work, Fourier transform infrared spectroscopy (FTIR) was used to identify characteristic absorption bands of the constituents and the crystallinity was evaluated by the X-ray diffraction (XRD) technique. The results indicated that appropriate ultrasonic pretreatment assisted with FeCl3 can enhance the acid hydrolysis of amorphous regions of cellulose, thus improving the crystallinity of the remaining hydrocellulose. It was observed that sonication samples that were pretreated for 300 W and 20 min followed by acid hydrolysis had maximum of 78.9% crystallinity. The crystallinity was 9.2% higher than samples that were not subjected to ultrasound. In addition, the average fines length decreased from 49 μm to 37 μm.

  13. Surface modified coals for enhanced catalyst dispersion and liquefaction. Semiannual progress report, September 1, 1995--February 29, 1996

    SciTech Connect

    Abotsi, G.M.K.

    1996-10-01

    The aim of this work is to enhance catalyst loading and dispersion in coal for improved liquefaction by preadsorption of surfactants onto coal. The application of surfactants to coal beneficiation and coal-water slurry preparation is well known. However, the effects of surfactants on catalyst loading and dispersion prior to coal liquefaction have not been investigated. The current work is focused on the influence of the cationic surfactant dodecyl dimethyl ethyl ammonium bromide (DDAB) and sodium dodecyl sulfate (SDS, anionic) on the surface properties of a bituminous coal and its molybdenum uptake from solution. The results show that DDAB created positively charged sites on the coal and increased molybdenum loading compared to the original coal. In contrast, SDS rendered the coal surface negative and reduced molybdenum uptake. The results show that efficient loading of molybdenum catalyst onto coal can be achieved by pretreatment of the coal with dodecyl dimethyl ethyl ammonium bromide.

  14. Molecular co-catalyst accelerating hole transfer for enhanced photocatalytic H2 evolution

    NASA Astrophysics Data System (ADS)

    Bi, Wentuan; Li, Xiaogang; Zhang, Lei; Jin, Tao; Zhang, Lidong; Zhang, Qun; Luo, Yi; Wu, Changzheng; Xie, Yi

    2015-10-01

    In artificial photocatalysis, sluggish kinetics of hole transfer and the resulting high-charge recombination rate have been the Achilles' heel of photocatalytic conversion efficiency. Here we demonstrate water-soluble molecules as co-catalysts to accelerate hole transfer for improved photocatalytic H2 evolution activity. Trifluoroacetic acid (TFA), by virtue of its reversible redox couple TFA./TFA-, serves as a homogeneous co-catalyst that not only maximizes the contact areas between co-catalysts and reactants but also greatly promotes hole transfer. Thus K4Nb6O17 nanosheet catalysts achieve drastically increased photocatalytic H2 production rate in the presence of TFA, up to 32 times with respect to the blank experiment. The molecular co-catalyst represents a new, simple and highly effective approach to suppress recombination of photogenerated charges, and has provided fertile new ground for creating high-efficiency photosynthesis systems, avoiding use of noble-metal co-catalysts.

  15. Molecular co-catalyst accelerating hole transfer for enhanced photocatalytic H2 evolution

    PubMed Central

    Bi, Wentuan; Li, Xiaogang; Zhang, Lei; Jin, Tao; Zhang, Lidong; Zhang, Qun; Luo, Yi; Wu, Changzheng; Xie, Yi

    2015-01-01

    In artificial photocatalysis, sluggish kinetics of hole transfer and the resulting high-charge recombination rate have been the Achilles' heel of photocatalytic conversion efficiency. Here we demonstrate water-soluble molecules as co-catalysts to accelerate hole transfer for improved photocatalytic H2 evolution activity. Trifluoroacetic acid (TFA), by virtue of its reversible redox couple TFA·/TFA−, serves as a homogeneous co-catalyst that not only maximizes the contact areas between co-catalysts and reactants but also greatly promotes hole transfer. Thus K4Nb6O17 nanosheet catalysts achieve drastically increased photocatalytic H2 production rate in the presence of TFA, up to 32 times with respect to the blank experiment. The molecular co-catalyst represents a new, simple and highly effective approach to suppress recombination of photogenerated charges, and has provided fertile new ground for creating high-efficiency photosynthesis systems, avoiding use of noble-metal co-catalysts. PMID:26486863

  16. Enhancing substrate utilization and power production of a microbial fuel cell with nitrogen-doped carbon aerogel as cathode catalyst.

    PubMed

    Tardy, Gábor Márk; Lóránt, Bálint; Lóka, Máté; Nagy, Balázs; László, Krisztina

    2017-07-01

    Catalytic efficiency of a nitrogen-doped, mesoporous carbon aerogel cathode catalyst was investigated in a two-chambered microbial fuel cell (MFC) applying graphite felt as base material for cathode and anode, utilizing peptone as carbon source. This mesoporous carbon aerogel containing catalyst layer on the cathode increased the maximum power density normalized to the anode volume to 2.7 times higher compared to the maximum power density obtained applying graphite felt cathode without the catalyst layer. At high (2 and 3) cathode/anode volume ratios, maximum power density exceeded 40 W m(-3). At the same time, current density and specific substrate utilization rate increased by 58% resulting in 31.9 A m(-3) and 18.8 g COD m(-3) h(-1), respectively (normalized to anode volume). Besides the increase of the power and the rate of biodegradation, the investigated catalyst decreased the internal resistance from the range of 450-600 to 350-370 Ω. Although Pt/C catalyst proved to be more efficient, a considerable decrease in the material costs might be achieved by substituting it with nitrogen-doped carbon aerogel in MFCs. Such cathode still displays enhanced catalytic effect.

  17. Radiofrequency treatment enhances the catalytic function of an immobilized nanobiohybrid catalyst

    NASA Astrophysics Data System (ADS)

    San, Boi Hoa; Ha, Eun-Ju; Paik, Hyun-Jong; Kim, Kyeong Kyu

    2014-05-01

    Biocatalysis, the use of enzymes in chemical transformation, has undergone intensive development for a wide range of applications. As such, maximizing the functionality of enzymes for biocatalysis is a major priority to enable industrial use. To date, many innovative technologies have been developed to address the future demand of enzymes for these purposes, but maximizing the catalytic activity of enzymes remains a challenge. In this study, we demonstrated that the functionality of a nanobiocatalyst could be enhanced by combining immobilization and radiofrequency (RF) treatment. Aminopeptidase PepA-encapsulating 2 nm platinum nanoparticles (PepA-PtNPs) with the catalytic activities of hydrolysis and hydrogenation were employed as multifunctional nanobiocatalysts. Immobilizing the nanobiocatalysts in a hydrogel using metal chelation significantly enhanced their functionalities, including catalytic power, thermal-stability, pH tolerance, organic solvent tolerance, and reusability. Most importantly, RF treatment of the hydrogel-immobilized PepA-PtNPs increased their catalytic power by 2.5 fold greater than the immobilized PepA. Our findings indicate that the catalytic activities and functionalities of PepA-PtNPs are greatly enhanced by the combination of hydrogel-immobilization and RF treatment. Based on our findings, we propose that RF treatment of nanobiohybrid catalysts immobilized on the bulk hydrogel represents a new strategy for achieving efficient biocatalysis.Biocatalysis, the use of enzymes in chemical transformation, has undergone intensive development for a wide range of applications. As such, maximizing the functionality of enzymes for biocatalysis is a major priority to enable industrial use. To date, many innovative technologies have been developed to address the future demand of enzymes for these purposes, but maximizing the catalytic activity of enzymes remains a challenge. In this study, we demonstrated that the functionality of a nanobiocatalyst

  18. Enhanced ethylene and ethane production with free-radical cracking catalysts.

    PubMed

    Kolts, J H; Delzer, G A

    1986-05-09

    A series of free-radical catalysts have been discovered that increase the yield of highly valuable olefins from the cracking of low molecular weight paraffins. For example, catalytic cracking of n-butane, isobutane, and propane over manganese or iron supported on magnesium oxide (MgO) gave product distributions different from those given by thermal (free-radical) cracking or cracking over traditional acid catalysts. With n-butane and propane feeds, the products from catalytic cracking included large amounts of ethylene and ethane; with isobutane feed, propylene was the major product. Physical characterization of the MgO-supported catalyst showed the manganese to be in a 2+ oxidation state in the reduced catalyst and a 4+ oxidation state in the fully oxidized catalyst. Manganese was also shown to be uniformly distributed in the support material with very little enrichment at the surface. Matrix isolation of the gasphase radicals from n-butane feed showed that ethyl and methyl radicals were produced over the active catalysts. In the thermal process, only methyl radicals were produced. The mechanism of the catalytic reaction appears to be selective formation of primary carbanions at the catalyst surface followed by electron transfer and release of primary hydrocarbon radicals to the gas phase.

  19. Purity-enhanced bulk synthesis of thin single-wall carbon nanotubes using iron-copper catalysts.

    PubMed

    Lim, H E; Miyata, Y; Nakayama, T; Chen, S; Kitaura, R; Shinohara, H

    2011-09-30

    We report high purity and high yield synthesis of single-wall carbon nanotubes (SWCNTs) of narrow diameter from iron-copper bimetal catalysts. The SWCNTs with diameter of 0.8-1.2 nm are synthesized using the zeolite-supported alcohol chemical vapour deposition method. Single metal and bimetal catalysts are systematically investigated to achieve both the enhancement of SWCNT yield and the suppression of the undesired formation of graphitic impurities. The relative yield and purity of SWCNTs are quantified using optical absorption spectroscopy with an ultracentrifuge-based purification technique. For the single metal catalyst, iron shows the highest catalytic activity compared with the other metals such as cobalt, nickel, molybdenum, copper, and platinum. It has been found that the addition of copper to iron results in the suppression of carbonaceous impurity formation without decreasing the SWCNT yield. The purity-enhanced SWCNT shows fairly low sheet resistance due to the improvement of inter-nanotube contacts. This scalable design of SWCNT synthesis with enhanced purity is therefore a promising tool for shaping future high performance devices.

  20. Purity-enhanced bulk synthesis of thin single-wall carbon nanotubes using iron-copper catalysts

    NASA Astrophysics Data System (ADS)

    Lim, H. E.; Miyata, Y.; Nakayama, T.; Chen, S.; Kitaura, R.; Shinohara, H.

    2011-09-01

    We report high purity and high yield synthesis of single-wall carbon nanotubes (SWCNTs) of narrow diameter from iron-copper bimetal catalysts. The SWCNTs with diameter of 0.8-1.2 nm are synthesized using the zeolite-supported alcohol chemical vapour deposition method. Single metal and bimetal catalysts are systematically investigated to achieve both the enhancement of SWCNT yield and the suppression of the undesired formation of graphitic impurities. The relative yield and purity of SWCNTs are quantified using optical absorption spectroscopy with an ultracentrifuge-based purification technique. For the single metal catalyst, iron shows the highest catalytic activity compared with the other metals such as cobalt, nickel, molybdenum, copper, and platinum. It has been found that the addition of copper to iron results in the suppression of carbonaceous impurity formation without decreasing the SWCNT yield. The purity-enhanced SWCNT shows fairly low sheet resistance due to the improvement of inter-nanotube contacts. This scalable design of SWCNT synthesis with enhanced purity is therefore a promising tool for shaping future high performance devices.

  1. Enhanced Activity and Durability of Nanosized Pt-SnO2/IrO2/CNTs Catalyst for Methanol Electrooxidation.

    PubMed

    Wang, Hongjuan; Wang, Xiaohui; Zheng, Jiadao; Peng, Feng; Yu, Hao

    2015-05-01

    Pt-SnO2/IrO2/CNTs anode catalyst for direct methanol fuel cell was designed and prepared with IrO2/CNTs as support for the subsequent immobilization of Pt and SnO2 at the same time. The structure of the catalysts and their catalytic performance in methanol electrooxidation were investigated and the roles of IrO2 and SnO2 in methanol electrooxidation were discussed as well. Results show that Pt-SnO2/IrO2/CNTs catalyst exhibits the best activity and durability for methanol electrooxidation when compared with Pt/CNTs, Pt/IrO2/CNTs and Pt-SnO2/CNTs. According to the results of electrochemical tests and physicochemical characterizations, the enhancements of Pt-SnO2/IrO2/CNTs were attributed to the special properties of IrO2 and SnO2, in which IrO2 mainly increases the methanol oxidation activity and SnO2 mainly improves the CO oxidation ability and durability. Therefore, Pt-SnO2/IrO2/CNTs exhibits excellent performance for methanol oxidation with higher electrocatalytic activity (I(f) of 1054 A g(Pt(-1)) and powerful anti-poisoning ability (the onset potential for CO oxidation of 0.3 V) and outstanding durability (the sustained time t in CP of 617 s), revealing a suitable anode catalyst for DMFCs.

  2. Synthesis of efficient silica supported TiO2/Ag2O heterostructured catalyst with enhanced photocatalytic performance

    NASA Astrophysics Data System (ADS)

    Zelekew, Osman Ahmed; Kuo, Dong-Hau; Yassin, Jemal Mohammed; Ahmed, Kedir Ebrahim; Abdullah, Hairus

    2017-07-01

    We develop the n-type TiO2 coated on SiO2 support abbreviated as SiO2/TiO2 (ST) followed by deposition of p-type Ag2O nanoparticles outside for the purpose of photocatalytic degradation of organic pollutants. Different composite catalysts were prepared with changing the amount AgNO3 (such as 0%, 5%, 10%, 20%, and 30%) and the composites were abbreviated as ST, STA-5, STA-10, STA-20, and STA-30, respectively. The composite catalysts were characterized with different techniques and tested for Rhodamine B (RhB) dye degradation under UV and visible light. Among the composite catalysts, the degradation efficiency of STA-20 was the highest and it degraded about 99% within 40 min under UV light-irradiation. However, the ST, STA-5, STA-10, and STA-30 composite catalysts could degrade about 21%, 47%, 58%, and 75% of the dye, respectively. Furthermore, the STA-5, STA-10, STA-20, and STA-30 composites were also tested and about 39%, 47%, 57%, and 42% of the dye, respectively, was degraded under visible light source. Hence, the formation of p-n junction heterostructure between n-type TiO2 and p-type Ag2O could enhance the degradation of RhB in both UV and visible light irradiation. It could be also potentially applicable photocatalyst for environmental remediation.

  3. Enhanced activity and selectivity of carbon nanofiber supported Pd catalysts for nitrite reduction.

    PubMed

    Shuai, Danmeng; Choe, Jong Kwon; Shapley, John R; Werth, Charles J

    2012-03-06

    Pd-based catalyst treatment represents an emerging technology that shows promise to remove nitrate and nitrite from drinking water. In this work we use vapor-grown carbon nanofiber (CNF) supports in order to explore the effects of Pd nanoparticle size and interior versus exterior loading on nitrite reduction activity and selectivity (i.e., dinitrogen over ammonia production). Results show that nitrite reduction activity increases by 3.1-fold and selectivity decreases by 8.0-fold, with decreasing Pd nanoparticle size from 1.4 to 9.6 nm. Both activity and selectivity are not significantly influenced by Pd interior versus exterior CNF loading. Consequently, turnover frequencies (TOFs) among all CNF catalysts are similar, suggesting nitrite reduction is not sensitive to Pd location on CNFs nor Pd structure. CNF-based catalysts compare favorably to conventional Pd catalysts (i.e., Pd on activated carbon or alumina) with respect to nitrite reduction activity and selectivity, and they maintain activity over multiple reduction cycles. Hence, our results suggest new insights that an optimum Pd nanoparticle size on CNFs balances faster kinetics with lower ammonia production, that catalysts can be tailored at the nanoscale to improve catalytic performance for nitrite, and that CNFs hold promise as highly effective catalyst supports in drinking water treatment.

  4. Bifunctional Ag/Fe/N/C Catalysts for Enhancing Oxygen Reduction via Cathodic Biofilm Inhibition in Microbial Fuel Cells.

    PubMed

    Dai, Ying; Chan, Yingzi; Jiang, Baojiang; Wang, Lei; Zou, Jinlong; Pan, Kai; Fu, Honggang

    2016-03-23

    Limitation of the oxygen reduction reaction (ORR) in single-chamber microbial fuel cells (SC-MFCs) is considered an important hurdle in achieving their practical application. The cathodic catalysts faced with a liquid phase are easily primed with the electrolyte, which provides more surface area for bacterial overgrowth, resulting in the difficulty in transporting protons to active sites. Ag/Fe/N/C composites prepared from Ag and Fe-chelated melamine are used as antibacterial ORR catalysts for SC-MFCs. The structure-activity correlations for Ag/Fe/N/C are investigated by tuning the carbonization temperature (600-900 °C) to clarify how the active-constituents of Ag/Fe and N-species influence the antibacterial and ORR activities. A maximum power density of 1791 mW m(-2) is obtained by Ag/Fe/N/C (630 °C), which is far higher than that of Pt/C (1192 mW m(-2)), only having a decline of 16.14% after 90 days of running. The Fe-bonded N and the cooperation of pyridinic N and pyrrolic N in Ag/Fe/N/C contribute equally to the highly catalytic activity toward ORR. The ·OH or O2(-) species originating from the catalysis of O2 can suppress the biofilm growth on Ag/Fe/N/C cathodes. The synergistic effects between the Ag/Fe heterojunction and N-species substantially contribute to the high power output and Coulombic efficiency of Ag/Fe/N/C catalysts. These new antibacterial ORR catalysts show promise for application in MFCs.

  5. Establishing Substantial Equivalence: Transcriptomics

    NASA Astrophysics Data System (ADS)

    Baudo, María Marcela; Powers, Stephen J.; Mitchell, Rowan A. C.; Shewry, Peter R.

    Regulatory authorities in Western Europe require transgenic crops to be substantially equivalent to conventionally bred forms if they are to be approved for commercial production. One way to establish substantial equivalence is to compare the transcript profiles of developing grain and other tissues of transgenic and conventionally bred lines, in order to identify any unintended effects of the transformation process. We present detailed protocols for transcriptomic comparisons of developing wheat grain and leaf material, and illustrate their use by reference to our own studies of lines transformed to express additional gluten protein genes controlled by their own endosperm-specific promoters. The results show that the transgenes present in these lines (which included those encoding marker genes) did not have any significant unpredicted effects on the expression of endogenous genes and that the transgenic plants were therefore substantially equivalent to the corresponding parental lines.

  6. Enhanced photocatalytic water oxidation efficiency with Ni(OH)₂ catalysts deposited on α-Fe₂O₃ via ALD.

    PubMed

    Young, Kelley M H; Hamann, Thomas W

    2014-08-14

    Atomic layer deposition was used to deposit NiO onto thin-film α-Fe2O3 electrodes for photocatalytic water splitting. Photoelectrochemical conditioning of the deposited NiO converts it to Ni(OH)2, which results in a stable reduction of the photocurrent onset potential for water oxidation by ~300 mV and improves photocurrent density by two-fold at 1.23 V vs. RHE as compared to untreated α-Fe2O3. This enhanced performance is shown to be due to improved charge separation with the ion-permeable Ni(OH)2 catalyst film. These results not only demonstrate one of the most effective water oxidation catalysts when integrated with hematite, but help establish the operational principles that lead to the improved performance.

  7. Enhanced photodegradation of pentachlorophenol by single and mixed nonionic and anionic surfactants using graphene-TiO₂ as catalyst.

    PubMed

    Zhang, Yaxin; He, Xin; Zeng, Guangming; Chen, Tan; Zhou, Zeyu; Wang, Hongtao; Lu, Wenjing

    2015-11-01

    The photodegradation of pentachlorophenol (PCP) in a surfactant-containing (single and mixed) complex system using graphene-TiO2 (GT) as catalyst was investigated. The objective was to better understand the behavior of surfactants in a GT catalysis system for its possible use in remediation technology of soil contaminated by hydrophobic organic compounds (HOCs). In a single-surfactant system, surfactant molecules aggregated on GT via hydrogen bonding and electrostatic force; nonideal mixing between nonionic and anionic surfactants rendered GT surface with mixed admicelles in a mixed surfactant system. Both effects helped incorporating PCP molecules into surfactant aggregates on catalyst surface. Hence, the targeted pollutants were rendered easily available to photo-yielded oxidative radicals, and photodegradation efficiency was significantly enhanced. Finally, real soil washing-photocatalysis trials proved that anionic-nonionic mixed surfactant soil washing coupled with graphene-TiO2 photocatalysis can be one promising technology for HOC-polluted soil remediation.

  8. Kinetics of oxygen-enhanced water gas shift on bimetallic catalysts and the roles of metals and support

    NASA Astrophysics Data System (ADS)

    Kugai, Junichiro

    The post-processing of reformate is an important step in producing hydrogen (H2) with low carbon monoxide (CO) for low temperature fuel cells from syn-gas. However, the conventional process consists of three steps, i.e. two steps of water gas shift (WGS) and preferential oxidation (PROX) of CO, and it is not suitable for mobile applications due to the large volume of water gas shift (WGS) catalysts and conditioning and/or regeneration necessary for these catalysts. Aiming at replacing those three steps by a simple one-step process, small amount of oxygen was added to WGS (the reaction called oxygen-enhanced water gas shift or OWGS) to promote the reaction kinetics and low pyrophoric ceria-supported bimetallic catalysts were employed for stable performance in this reaction. Not only CO conversion, but also H2 yield was found to increase by the O2 addition on CeO2-supported catalysts. The characteristics of OWGS, high H2 production rate at 200 to 300°C at short contact time where unreacted O2 exists, evidenced the impact of O2 addition on surface species on the catalyst. Around 1.5 of reaction order in CO for various CeO2-supported metal catalysts for OWGS compared to reaction orders in CO ranging from -0.1 to 0.6 depending on metal species for WGS shows O2 addition decreases CO coverage to free up the active sites for co-reactant (H2O) adsorption and activation. Among the monometallic and bimetallic catalysts, Pt-Cu and Pd-Cu bimetallic catalysts were superior to monometallic catalysts in OWGS. These bimetallic components were found to form alloys where noble metal is surrounded mainly by Cu to have strong interaction between noble metal and copper resulting in high OWGS activity and low pyrophoric property. The metal loadings were optimized for CeO2-supported Pd-Cu bimetallic system and 2 wt% Pd with 5 -- 10 wt% Cu were found to be the optimum for the present OWGS condition. In the kinetic study, Pd in Pd-Cu was shown to increase the active sites for H2O

  9. Host cell and expression engineering for development of an E. coli ketoreductase catalyst: enhancement of formate dehydrogenase activity for regeneration of NADH.

    PubMed

    Mädje, Katharina; Schmölzer, Katharina; Nidetzky, Bernd; Kratzer, Regina

    2012-01-11

    Enzymatic NADH or NADPH-dependent reduction is a widely applied approach for the synthesis of optically active organic compounds. The overall biocatalytic conversion usually involves in situ regeneration of the expensive NAD(P)H. Oxidation of formate to carbon dioxide, catalyzed by formate dehydrogenase (EC 1.2.1.2; FDH), presents an almost ideal process solution for coenzyme regeneration that has been well established for NADH. Because isolated FDH is relatively unstable under a range of process conditions, whole cells often constitute the preferred form of the biocatalyst, combining the advantage of enzyme protection in the cellular environment with ease of enzyme production. However, the most prominent FDH used in biotransformations, the enzyme from the yeast Candida boidinii, is usually expressed in limiting amounts of activity in the prime host for whole cell biocatalysis, Escherichia coli. We therefore performed expression engineering with the aim of enhancing FDH activity in an E. coli ketoreductase catalyst. The benefit resulting from improved NADH regeneration capacity is demonstrated in two transformations of technological relevance: xylose conversion into xylitol, and synthesis of (S)-1-(2-chlorophenyl)ethanol from o-chloroacetophenone. As compared to individual expression of C. boidinii FDH in E. coli BL21 (DE3) that gave an intracellular enzyme activity of 400 units/g(CDW), co-expression of the FDH with the ketoreductase (Candida tenuis xylose reductase; XR) resulted in a substantial decline in FDH activity. The remaining FDH activity of only 85 U/g(CDW) was strongly limiting the overall catalytic activity of the whole cell system. Combined effects from increase in FDH gene copy number, supply of rare tRNAs in a Rosetta strain of E. coli, dampened expression of the ketoreductase, and induction at low temperature (18°C) brought up the FDH activity threefold to a level of 250 U/g(CDW) while reducing the XR activity by just 19% (1140 U/g(CDW)). The E

  10. Enhanced removal of sodium salts supported by in-situ catalyst synthesis in a supercritical water oxidation process.

    PubMed

    Takahashi, F; Sun, Z R; Fukushi, K; Oshima, Y; Yamamoto, K

    2012-01-01

    For practical applications of supercritical water oxidation to wastewater treatment, the deposition of inorganic salts in supercritical phase must be controlled to prevent a reactor from clogging. This study investigated enhanced removal of sodium salts with titanium particles, serving as a salt trapper and a catalyst precursor, and sodium recovery by sub-critical water. When Na(2)CO(3) was tested as a model salt, sodium removal efficiency was higher than theoretically maximum efficiency defined by Na(2)CO(3) solubility. The enhanced sodium removal resulted from in-situ synthesis of sodium titanate, which could catalyse acetic acid oxidation. The kinetics of sodium removal was described well by a diffusion mass-transfer model combined with a power law-type rate model of sodium titanate synthesis. Titanium particles showed positive effect on sodium removal in the case of NaOH, Na(2)SO(4) and Na(3)PO(4). However, they had negligible effect for NaCl and negative effect for Na(2)CrO(4), respectively. More than 99% of trapped sodium was recovered by sub-critical water except for Na(2)CrO(4). In contrast, sodium recovery efficiency remained less than 50% in the case of Na(2)CrO(4). Reused titanium particles showed the same performance for enhanced sodium removal. Enhanced salt removal supported by in-situ catalyst synthesis has great potential to enable both salt removal control and catalytic oxidation.

  11. Enhanced Oxygen Reduction Activity In Acid By Tin-Oxide Supported Au Nanoparticle Catalysts

    SciTech Connect

    Baker,W.; Pietron, J.; Teliska, M.; Bouwman, P.; Ramaker, D.; Swider-Lyons, K.

    2006-01-01

    Gold nanoparticles supported on hydrous tin-oxide (Au-SnO{sub x}) are active for the four-electron oxygen reduction reaction in an acid electrolyte. The unique electrocatalytic of the Au-SnO is confirmed by the low amount of peroxide detected with rotating ring-disk electrode voltammetry and Koutecky-Levich analysis. In comparison, 10 wt % Au supported on Vulcan carbon and SnO{sub x} catalysts both produce significant peroxide in the acid electrolyte, indicating only a two-electron reduction reaction. Characterization of the Au-SnO{sub x} catalyst reveals a high-surface area, amorphous support with 1.7 nm gold metal particles. The high catalytic activity of the Au-SnO is attributed to metal support interactions. The results demonstrate a possible path to non-Pt catalysts for proton exchange membrane fuel cell cathodes.

  12. Microwave enhanced alcoholysis of non-edible (algal, jatropha and pongamia) oils using chemically activated egg shell derived CaO as heterogeneous catalyst.

    PubMed

    Joshi, Girdhar; Rawat, Devendra S; Sharma, Amit Kumar; Pandey, Jitendra K

    2016-11-01

    Microwave enhanced fast and efficient alcoholysis (methanolysis and ethanolysis) of non-edible oils (algal, jatropha and pongamia) is achieved using chemically activated waste egg shell derived CaO (i.e. CaO(cesp)) as heterogeneous catalyst. CaO(cesp) was extracted from waste chicken egg shell and further activated chemically by supporting transition metal oxide. The maximum conversion was achieved using 3wt% catalysts under 700W microwave irradiation and 10:1 alcohol/oil ratio in 6min. Alcoholysis using ZnO activated CaO(cesp) catalyst has shown higher reaction yields in comparison to other modified catalysts. Methanolysis has shown better biodiesel conversion in comparison to ethanolysis. The catalyst has shown longer lifetime and sustained activity after being used for four cycles. Due to more saturated fatty acid content; algal biodiesel has shown improved fuel properties in comparison to other biodiesels. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Enhancement of nitric oxide decomposition efficiency achieved with lanthanum-based perovskite-type catalyst.

    PubMed

    Pan, Kuan Lun; Chen, Mei Chung; Yu, Sheng Jen; Yan, Shaw Yi; Chang, Moo Been

    2016-06-01

    Direct decompositions of nitric oxide (NO) by La0.7Ce0.3SrNiO4, La0.4Ba0.4Ce0.2SrNiO4, and Pr0.4Ba0.4Ce0.2SrNiO4 are experimentally investigated, and the catalysts are tested with different operating parameters to evaluate their activities. Experimental results indicate that the physical and chemical properties of La0.7Ce0.3SrNiO4 are significantly improved by doping with Ba and partial substitution with Pr. NO decomposition efficiencies achieved with La0.4Ba0.4Ce0.2SrNiO4 and Pr0.4Ba0.4Ce0.2SrNiO4 are 32% and 68%, respectively, at 400 °C with He as carrier gas. As the temperature is increased to 600 °C, NO decomposition efficiencies achieved with La0.4Ba0.4Ce0.2SrNiO4 and Pr0.4Ba0.4Ce0.2SrNiO4, respectively, reach 100% with the inlet NO concentration of 1000 ppm while the space velocity is fixed at 8000 hr(-1). Effects of O2, H2O(g), and CO2 contents and space velocity on NO decomposition are also explored. The results indicate that NO decomposition efficiencies achieved with La0.4Ba0.4Ce0.2SrNiO4 and Pr0.4Ba0.4Ce0.2SrNiO4, respectively, are slightly reduced as space velocity is increased from 8000 to 20,000 hr(-1) at 500 °C. In addition, the activities of both catalysts (La0.4Ba0.4Ce0.2SrNiO4 and Pr0.4Ba0.4Ce0.2SrNiO4) for NO decomposition are slightly reduced in the presence of 5% O2, 5% CO2, or 5% H2O(g). For durability test, with the space velocity of 8000 hr(-1) and operating temperature of 600 °C, high N2 yield is maintained throughout the durability test of 60 hr, revealing the long-term stability of Pr0.4Ba0.4Ce0.2SrNiO4 for NO decomposition. Overall, Pr0.4Ba0.4Ce0.2SrNiO4 shows good catalytic activity for NO decomposition. Nitrous oxide (NO) not only causes adverse environmental effects such as acid rain, photochemical smog, and deterioration of visibility and water quality, but also harms human lungs and respiratory system. Pervoskite-type catalysts, including La0.7Ce0.3SrNiO4, La0.4Ba0.4Ce0.2SrNiO4, and Pr0.4Ba0.4Ce0.2SrNiO4, are applied for direct

  14. Establishing Substantial Equivalence: Metabolomics

    NASA Astrophysics Data System (ADS)

    Beale, Michael H.; Ward, Jane L.; Baker, John M.

    Modern ‘metabolomic’ methods allow us to compare levels of many structurally diverse compounds in an automated fashion across a large number of samples. This technology is ideally suited to screening of populations of plants, including trials where the aim is the determination of unintended effects introduced by GM. A number of metabolomic methods have been devised for the determination of substantial equivalence. We have developed a methodology, using [1H]-NMR fingerprinting, for metabolomic screening of plants and have applied it to the study of substantial equivalence of field-grown GM wheat. We describe here the principles and detail of that protocol as applied to the analysis of flour generated from field plots of wheat. Particular emphasis is given to the downstream data processing and comparison of spectra by multivariate analysis, from which conclusions regarding metabolome changes due to the GM can be assessed against the background of natural variation due to environment.

  15. C-H functionalization: thoroughly tuning ligands at a metal ion, a chemist can greatly enhance catalyst's activity and selectivity.

    PubMed

    Shul'pin, Georgiy B

    2013-09-28

    This brief essay consists of a few "exciting stories" devoted to relations within a metal-complex catalyst between a metal ion and a coordinated ligand. When, as in the case of a human couple, the rapport of the partners is cordial and a love cements these relations, a chemist finds an ideal married couple, in other words he obtains a catalyst of choice which allows him to functionalize C-H bonds very efficiently and selectively. Examples of such lucky marriages in the catalytic world of ions and ligands are discussed here. Activity of the catalyst is characterized by turnover number (TON) or turnover frequency (TOF) as well as by yield of a target product. Introducing a chelating N,N- or N,O-ligand to the catalyst molecule (this can be an iron or manganese derivative) sharply enhances its activity. However, the activity of vanadium derivatives (with additionally added to the solution pyrazinecarboxylic acid, PCA) as well as of various osmium complexes does not dramatically depend on the nature of ligands surrounding metal ions. Complexes of these metals are very efficient catalysts in oxidations with H2O2. Osmium derivatives are record-holders exhibiting extremely high TONs whereas vanadium complexes are on the second position. Finally, elegant examples of alkane functionalization on the ions of non-transition metals (aluminium, gallium etc.) are described when one ligand within the metal complex (namely, hydroperoxyl ligand HOO(-)) helps other ligand of this complex (H2O2 molecule coordinated to the metal) to disintegrate into two species, generating very reactive hydroxyl radical. Hydrogen peroxide molecule, even ligated to the metal ion, is perfectly stable without the assistance of the neighboring HOO(-) ligand. This ligand can be easily oxidized donating an electron to its partner ligand (H2O2). In an analogous case, when the central ion in the catalyst is a transition metal, this ion changing its oxidation state can donate an electron to the coordinated H2O2

  16. Enhanced electrocatalytic performance of processed, ultrathin, supported Pd-Pt core-shell nanowire catalysts for the oxygen reduction reaction.

    PubMed

    Koenigsmann, Christopher; Santulli, Alexander C; Gong, Kuanping; Vukmirovic, Miomir B; Zhou, Wei-ping; Sutter, Eli; Wong, Stanislaus S; Adzic, Radoslav R

    2011-06-29

    We report on the synthesis, characterization, and electrochemical performance of novel, ultrathin Pt monolayer shell-Pd nanowire core catalysts. Initially, ultrathin Pd nanowires with diameters of 2.0 ± 0.5 nm were generated, and a method has been developed to achieve highly uniform distributions of these catalysts onto the Vulcan XC-72 carbon support. As-prepared wires are activated by the use of two distinctive treatment protocols followed by selective CO adsorption in order to selectively remove undesirable organic residues. Subsequently, the desired nanowire core-Pt monolayer shell motif was reliably achieved by Cu underpotential deposition followed by galvanic displacement of the Cu adatoms. The surface area and mass activity of the acid and ozone-treated nanowires were assessed, and the ozone-treated nanowires were found to maintain outstanding area and mass specific activities of 0.77 mA/cm(2) and 1.83 A/mg(Pt), respectively, which were significantly enhanced as compared with conventional commercial Pt nanoparticles, core-shell nanoparticles, and acid-treated nanowires. The ozone-treated nanowires also maintained excellent electrochemical durability under accelerated half-cell testing, and it was found that the area-specific activity increased by ~1.5 fold after a simulated catalyst lifetime.

  17. Tuning the Composition of Electrodeposited Bimetallic Tin-Lead Catalysts for Enhanced Activity and Durability in Carbon Dioxide Electroreduction to Formate.

    PubMed

    Moore, Colin E; Gyenge, Előd L

    2017-09-11

    Bimetallic Sn-Pb catalysts with five different Sn/Pb atomic ratios were electrodeposited on Teflonated carbon paper and non-Teflonated carbon cloth using both fluoroborate- and oxide-containing deposition media to produce catalysts for the electrochemical reduction of CO2 (ERC) to formate (HCOO(-) ). The interaction between catalyst composition, morphology, substrate, and deposition media was investigated by using cyclic voltammetry and constant potential electrolysis at -2.0 V versus Ag/AgCl for 2 h in 0.5 m KHCO3 . The catalysts were analyzed before and after electrolysis by using SEM and XRD to determine the mechanisms of Faradaic efficiency loss and degradation. Catalysts that are mainly Sn with 15-35 at % Pb generated Faradaic efficiencies up to 95 % with a stable performance. However, pure Sn catalysts showed high initial stage formate production rates but experienced an extensive (up to 30 %) decrease of the Faradaic efficiency. The XRD results demonstrated the presence of polycrystalline SnO2 after electrolysis using Sn-Pb catalysts with 35 at % Pb and its absence in the case of pure Sn. It is proposed that the presence of Pb (15-35 at %) in mainly Sn catalysts stabilized SnO2 , which is responsible for the enhanced Faradaic efficiency and catalytic durability in the ERC. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Enhanced High- and Low-Temperature Performance of NOx Reduction Catalyst Materials

    SciTech Connect

    Gao, Feng; Muntean, George G.; Peden, Charles HF; Howden, Ken; Currier, Neal; Kamasamudram, Krishna; Kumar, Ashok; Li, Junhui; Luo, Jinyong; Stafford, Randy; Yezerets, Aleksey; Castagnola, Mario; Chen, Hai-Ying; Hess, Howard ..

    2014-12-09

    In this annual CRADA program report, we will briefly highlight results from our recent studies of the stability of candidate K-based high temperature NSR materials, and comparative studies of low temperature performance of SSZ-13 and SAPO-34 CHA catalysts; in particular, recent results comparing Fe- and Cu-based CHA materials.

  19. ENHANCING THE STABILITY OF POROUS CATALYSTS WITH SUPERCRITICAL REACTION MEDIA. (R826034)

    EPA Science Inventory

    Adsorption/desorption and pore-transport are key parameters influencing the activity and product selectivity in porous catalysts. With conventional reaction media (gas or liquid phase), one of these parameters is generally favorable while the other is not. For instance, while ...

  20. ENHANCING THE STABILITY OF POROUS CATALYSTS WITH SUPERCRITICAL REACTION MEDIA. (R826034)

    EPA Science Inventory

    Adsorption/desorption and pore-transport are key parameters influencing the activity and product selectivity in porous catalysts. With conventional reaction media (gas or liquid phase), one of these parameters is generally favorable while the other is not. For instance, while ...

  1. Dominance of Plasmonic Resonant Energy Transfer over Direct Electron Transfer in Substantially Enhanced Water Oxidation Activity of BiVO4 by Shape-Controlled Au Nanoparticles.

    PubMed

    Lee, Mi Gyoung; Moon, Cheon Woo; Park, Hoonkee; Sohn, Woonbae; Kang, Sung Bum; Lee, Sanghan; Choi, Kyoung Jin; Jang, Ho Won

    2017-10-01

    The performance of plasmonic Au nanostructure/metal oxide heterointerface shows great promise in enhancing photoactivity, due to its ability to confine light to the small volume inside the semiconductor and modify the interfacial electronic band structure. While the shape control of Au nanoparticles (NPs) is crucial for moderate bandgap semiconductors, because plasmonic resonance by interband excitations overlaps above the absorption edge of semiconductors, its critical role in water splitting is still not fully understood. Here, first, the plasmonic effects of shape-controlled Au NPs on bismuth vanadate (BiVO4 ) are studied, and a largely enhanced photoactivity of BiVO4 is reported by introducing the octahedral Au NPs. The octahedral Au NP/BiVO4 achieves 2.4 mA cm(-2) at the 1.23 V versus reversible hydrogen electrode, which is the threefold enhancement compared to BiVO4 . It is the highest value among the previously reported plasmonic Au NPs/BiVO4 . Improved photoactivity is attributed to the localized surface plasmon resonance; direct electron transfer (DET), plasmonic resonant energy transfer (PRET). The PRET can be stressed over DET when considering the moderate bandgap semiconductor. Enhanced water oxidation induced by the shape-controlled Au NPs is applicable to moderate semiconductors, and shows a systematic study to explore new efficient plasmonic solar water splitting cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Immobilization of a Metal-Nitrogen-Carbon Catalyst on Activated Carbon with Enhanced Cathode Performance in Microbial Fuel Cells.

    PubMed

    Yang, Wulin; Logan, Bruce E

    2016-08-23

    Applications of microbial fuel cells (MFCs) are limited in part by low power densities mainly due to cathode performance. Successful immobilization of an Fe-N-C co-catalyst on activated carbon (Fe-N-C/AC) improved the oxygen reduction reaction to nearly a four-electron transfer, compared to a twoelectron transfer achieved using AC. With acetate as the fuel, the maximum power density was 4.7±0.2 W m(-2) , which is higher than any previous report for an air-cathode MFC. With domestic wastewater as a fuel, MFCs with the Fe-N-C/AC cathode produced up to 0.8±0.03 W m(-2) , which was twice that obtained with a Pt-catalyzed cathode. The use of this Fe-N-C/AC catalyst can therefore substantially increase power production, and enable broader applications of MFCs for renewable electricity generation using waste materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. CATALYSIS SCIENCE INITIATIVE: From First Principles Design to Realization of Bimetallic Catalysts for Enhanced Selectivity

    SciTech Connect

    MAVRIKAKIS, MANOS DUMESIC, JAMES A.

    2007-05-03

    In this project, we have integrated state-of-the-art Density Functional Theory (DFT) models of heterogeneous catalytic processes with high-throughput screening of bimetallic catalytic candidates for important industrial problems. We have studied a new class of alloys characterized by a surface composition different from the bulk composition, and investigated their stability and activity for the water-gas shift reaction and the oxygen reduction reaction. The former reaction is an essential part of hydrogen production; the latter is the rate-limiting step in low temperature H2 fuel cells. We have identified alloys that have remarkable stability and activity, while having a much lower material cost for both of these reactions. Using this knowledge of bimetallic interactions, we have also made progress in the industrially relevant areas of carbohydrate reforming and conversion of biomass to liquid alkanes. One aspect of this work is the conversion of glycerol (a byproduct of biodiesel production) to synthesis gas. We have developed a bifunctional supported Pt catalyst that can cleave the carbon-carbon bond while also performing the water-gas shift reaction, which allows us to better control the H2:CO ratio. Knowledge gained from the theoretical metal-metal interactions was used to develop bimetallic catalysts that perform this reaction at low temperature, allowing for an efficient coupling of this endothermic reaction with other reactions, such as Fischer-Tropsch or methanol synthesis. In our work on liquid alkane production from biomass, we have studied deactivation and selectivity in these areas as a function of metal-support interactions and reaction conditions, with an emphasis on the bifunctionality of the catalysts studied. We have identified a stable, active catalyst for this process, where the selectivity and yield can be controlled by the reaction conditions. While complete rational design of catalysts is still elusive, this work demonstrates the power of

  4. Establishing Substantial Equivalence: Proteomics

    NASA Astrophysics Data System (ADS)

    Lovegrove, Alison; Salt, Louise; Shewry, Peter R.

    Wheat is a major crop in world agriculture and is consumed after processing into a range of food products. It is therefore of great importance to determine the consequences (intended and unintended) of transgenesis in wheat and whether genetically modified lines are substantially equivalent to those produced by conventional plant breeding. Proteomic analysis is one of several approaches which can be used to address these questions. Two-dimensional PAGE (2D PAGE) remains the most widely available method for proteomic analysis, but is notoriously difficult to reproduce between laboratories. We therefore describe methods which have been developed as standard operating procedures in our laboratory to ensure the reproducibility of proteomic analyses of wheat using 2D PAGE analysis of grain proteins.

  5. Reducible oxide based catalysts

    DOEpatents

    Thompson, Levi T.; Kim, Chang Hwan; Bej, Shyamal K.

    2010-04-06

    A catalyst is disclosed herein. The catalyst includes a reducible oxide support and at least one noble metal fixed on the reducible oxide support. The noble metal(s) is loaded on the support at a substantially constant temperature and pH.

  6. Nickel phosphide nanoparticles-nitrogen-doped graphene hybrid as an efficient catalyst for enhanced hydrogen evolution activity

    NASA Astrophysics Data System (ADS)

    Pan, Yuan; Yang, Na; Chen, Yinjuan; Lin, Yan; Li, Yanpeng; Liu, Yunqi; Liu, Chenguang

    2015-11-01

    Development of hybrid catalysts with high activity, good stability and low cost is extremely desirable for hydrogen production by electrolysis of water. In this work, a hybrid composed of Ni2P nanoparticles (NPs) on N-doped reduced graphene oxide (NRGO) is synthesized via an in situ thermal decomposition approach for the first time and investigated as a catalyst for the hydrogen evolution reaction (HER). The as-synthesized Ni2P/NRGO hybrid exhibits an enhanced catalytic activity with low onset overpotential (37 mV), a small Tafel slope (59 mV dec-1), a much larger exchange current density (4.9 × 10-5 A cm-2), and lower HER activation energy (46.9 kJ mol-1) than Ni2P/RGO hybrid. In addition, the Ni2P/NRGO hybrid maintains its catalytic activity for at least 60‧000 s in acidic media. The enhanced catalytic activity is attributed to the synergistic effect of N-doped RGO and Ni2P NPs, the charged natures of Ni and P, as well as the high electrical conductivity of Ni2P/NRGO hybrid. This study may offer a new strategy for improving the electrocatalytic activity for hydrogen production.

  7. Enhanced Performance of non-PGM Catalysts in Air Operated PEM-Fuel Cells

    DOE PAGES

    Barkholtz, Heather M.; Chong, Lina; Kaiser, Zachary Brian; ...

    2016-10-13

    Here a non-platinum group metal (non-PGM) oxygen reduction catalyst was prepared from “support-free” zeolitic imidazolate framework (ZIF) precursor and tested in the proton exchange membrane fuel cell with air as the cathode feed. The iron nitrogen and carbon composite (FeeNeC) based catalyst has high specific surface area decorated uniformly with active sites, which redefines the triple phase boundary (TPB) and requires re-optimization of the cathodic membrane electrode fabrication to ensure efficient mass and charge transports to the catalyst surface. This study reports an effort in optimizing catalytic ink formulation for the membrane electrode preparation and its impact to the fuelmore » cell performance under air. Through optimization, the fuel cell areal current density as high as 115.2 mA/cm2 at 0.8 V or 147.6 mA/cm2 at 0.8 ViR-free has been achieved under one bar air. We also investigated impacts on fuel cell internal impedance and the water formation.« less

  8. Enhanced Performance of non-PGM Catalysts in Air Operated PEM-Fuel Cells

    SciTech Connect

    Barkholtz, Heather M.; Chong, Lina; Kaiser, Zachary Brian; Xu, Tao; Liu, Di-Jia

    2016-10-13

    Here a non-platinum group metal (non-PGM) oxygen reduction catalyst was prepared from “support-free” zeolitic imidazolate framework (ZIF) precursor and tested in the proton exchange membrane fuel cell with air as the cathode feed. The iron nitrogen and carbon composite (FeeNeC) based catalyst has high specific surface area decorated uniformly with active sites, which redefines the triple phase boundary (TPB) and requires re-optimization of the cathodic membrane electrode fabrication to ensure efficient mass and charge transports to the catalyst surface. This study reports an effort in optimizing catalytic ink formulation for the membrane electrode preparation and its impact to the fuel cell performance under air. Through optimization, the fuel cell areal current density as high as 115.2 mA/cm2 at 0.8 V or 147.6 mA/cm2 at 0.8 ViR-free has been achieved under one bar air. We also investigated impacts on fuel cell internal impedance and the water formation.

  9. Enhanced Performance of non-PGM Catalysts in Air Operated PEM-Fuel Cells

    SciTech Connect

    Barkholtz, Heather M.; Chong, Lina; Kaiser, Zachary Brian; Xu, Tao; Liu, Di-Jia

    2016-10-13

    Here a non-platinum group metal (non-PGM) oxygen reduction catalyst was prepared from “support-free” zeolitic imidazolate framework (ZIF) precursor and tested in the proton exchange membrane fuel cell with air as the cathode feed. The iron nitrogen and carbon composite (FeeNeC) based catalyst has high specific surface area decorated uniformly with active sites, which redefines the triple phase boundary (TPB) and requires re-optimization of the cathodic membrane electrode fabrication to ensure efficient mass and charge transports to the catalyst surface. This study reports an effort in optimizing catalytic ink formulation for the membrane electrode preparation and its impact to the fuel cell performance under air. Through optimization, the fuel cell areal current density as high as 115.2 mA/cm2 at 0.8 V or 147.6 mA/cm2 at 0.8 ViR-free has been achieved under one bar air. We also investigated impacts on fuel cell internal impedance and the water formation.

  10. Enhanced catalytic performance of Pd catalyst for formic acid electrooxidation in ionic liquid aqueous solution

    NASA Astrophysics Data System (ADS)

    Feng, Yuan-Yuan; Yin, Qian-Ying; Lu, Guo-Ping; Yang, Hai-Fang; Zhu, Xiao; Kong, De-Sheng; You, Jin-Mao

    2014-12-01

    A protic ionic liquid (IL), n-butylammonium nitrate (N4NO3), is prepared and employed as the electrolyte for formic acid electrooxidation reaction (FAOR) on Pd catalysts. The oxidation peak potential of FAOR in the IL solution shows about a 200 mV negative shift as compared with those in traditional H2SO4/HClO4 electrolytes, suggesting that FAOR can be more easily carried out on Pd catalysts in IL media. The catalytic properties of Pd toward FAOR are not only dependent on the concentration of IL, as a consequence of the varied electronic conductivity of the IL solution, but also on the high potential limit of the cyclic voltammograms. When the Pd catalyst is cycled up to 1.0 V (vs. SCE), which induces a significant oxidation of Pd, it shows ca. 4.0 times higher activity than that not subjected to the Pd oxidation (up to 0.6 V). The Pd oxides, which are more easily formed in IL solution than in traditional H2SO4/HClO4 electrolytes, may play a crucial role in increasing the catalytic activities of Pd toward FAOR. Our work would shed new light on the mechanism of FAOR and highlight the potential applications of IL as green and environment-friendly electrolytes in fuel cells and other technologies.

  11. Enhancement of anodic oxidation of formic acid on palladium decorated Pt/C catalyst

    NASA Astrophysics Data System (ADS)

    Wu, Yan Ni; Liao, Shi Jun; Su, Yun Lan; Zeng, Jian Huang; Dang, Dai

    A palladium decorated Pt/C catalyst, Pt@Pd/C, is prepared by a colloidal approach with a small amount of platinum as core. It is found that the catalyst shows excellent activity towards anodic oxidation of formic acid at room temperature and its activity is 60% higher than that of Pd/C. Decoration of palladium shell on the platinum core is supported by XPS results. Due to the use of platinum as core, active components are dispersed very well and the particle sizes are smaller than those of Pd/C. The cyclic voltammetry measurement clearly shows synthetic electro-oxidation effects of formic acid on Pt@Pd/C. It is speculated that the high performance of Pt@Pd/C may result from the unique core-shell structure and synergistic effect of Pt and Pd at the interface. The preparation method for Pt@Pd/C reported in this work will provide additional options for the design of catalysts for direct formic acid fuel cell (DFAFC).

  12. Substantial enhancement of energy storage capability in polymer nanocomposites by encapsulation of BaTiO3 NWs with variable shell thickness.

    PubMed

    Wang, Guanyao; Huang, Yanhui; Wang, Yuxin; Jiang, Pingkai; Huang, Xingyi

    2017-08-09

    Dielectric polymer nanocomposites have received keen interest due to their potential application in energy storage. Nevertheless, the large contrast in dielectric constant between the polymer and nanofillers usually results in a significant decrease of breakdown strength of the nanocomposites, which is unfavorable for enhancing energy storage capability. Herein, BaTiO3 nanowires (NWs) encapsulated by TiO2 shells of variable thickness were utilized to fabricate dielectric polymer nanocomposites. Compared with nanocomposites with bare BaTiO3 NWs, significantly enhanced energy storage capability was achieved for nanocomposites with TiO2 encapsulated BaTiO3 NWs. For instance, an ultrahigh energy density of 9.53 J cm(-3) at 440 MV m(-1) could be obtained for nanocomposites comprising core-shell structured nanowires, much higher than that of nanocomposites with 5 wt% raw ones (5.60 J cm(-3) at 360 MV m(-1)). The discharged energy density of the proposed nanocomposites with 5 wt% mTiO2@BaTiO3-1 NWs at 440 MV m(-1) seems to rival or exceed those of some previously reported nanocomposites (mostly comprising core-shell structured nanofillers). More notably, this study revealed that the energy storage capability of the nanocomposites can be tailored by the TiO2 shell thickness. Finite element simulations were employed to analyze the electric field distribution in the nanocomposites. The enhanced energy storage capability should be mainly attributed to the smoother gradient of dielectric constant between the nanofillers and polymer matrix, which alleviated the electric field concentration and leakage current in the polymer matrix. The methods and results herein offer a feasible approach to construct high-energy-density polymer nanocomposites with core-shell structured nanowires.

  13. Crystalline titanate catalyst supports

    DOEpatents

    Anthony, Rayford G.; Dosch, Robert G.

    1993-01-01

    A series of new crystalline titanates (CT) are shown to have considerable potential as catalyst supports. For Pd supported catalyst, the catalytic activity for pyrene hydrogenation was substantially different depending on the type of CT, and one was substantially more active than Pd on hydrous titanium oxide (HTO). For 1-hexene hydrogenation the activities of the new CTs were approximately the same as for the hydrous metal oxide supports.

  14. Crystalline titanate catalyst supports

    DOEpatents

    Anthony, R.G.; Dosch, R.G.

    1993-01-05

    A series of new crystalline titanates (CT) are shown to have considerable potential as catalyst supports. For Pd supported catalyst, the catalytic activity for pyrene hydrogenation was substantially different depending on the type of CT, and one was substantially more active than Pd on hydrous titanium oxide (HTO). For 1-hexene hydrogenation the activities of the new CTs were approximately the same as for the hydrous metal oxide supports.

  15. Catalyst evaluation for high-purity H2 production by sorption-enhanced steam-methane reforming coupled to a Ca/Cu process

    NASA Astrophysics Data System (ADS)

    Navarro, M. V.; López, J. M.; García, T.; Grasa, G.; Murillo, R.

    2017-09-01

    The operational limits of a commercial nickel-based catalyst under the conditions of a sorption-enhanced steam-methane reforming process coupled to a Ca/Cu chemical loop are investigated for high-purity H2 production in a cyclic operation. The performance of the reforming catalyst is tested by means of a high number of oxidation-reduction-reforming cycles. After 100 oxidation-reduction cycles, this catalyst retains its exceptional reforming activity. The methane conversion values are close to the thermodynamic equilibrium under very demanding conditions: temperature between 500 °C - 700 °C and mass hourly space velocity of 8.8 kgCH4 h-1 kgcat-1. After 200 cycles, the sample shows reduction in its reforming activity in line with a lower dispersion of the Ni species. Sintering of Ni nanocrystals is evidenced during the oxidation-reduction multi-cycles. The performance of the catalyst after 200 oxidation-reduction cycles mixed with a CaO-based CO2 sorbent is studied under optimal conditions calculated for the sorption-enhanced reforming process coupled to a Ca/Cu cycle (temperature of 650 °C, steam/methane ratio of 4, sorbent/catalyst ratio of 4 and space velocity of 0.75 kgCH4 h-1 kgcat-1). Remarkably, an equilibrium value over 92 vol.% H2 concentration is achieved, highlighting this catalyst as a promising candidate for the next steps of the process development.

  16. Enhanced hydrothermal stability of Cu-ZSM-5 catalyst via surface modification in the selective catalytic reduction of NO with NH3

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Shi, Juan; Liu, Jian; Wang, Daxi; Zhao, Zhen; Cheng, Kai; Li, Jianmei

    2016-07-01

    The surface of Cu-ZSM-5 catalyst was modified by chemical liquid deposition (CLD) of tetraethoxysilane (TEOS) for enhancing its hydrothermal stability in the selective catalytic reduction of NO with NH3. After hydrothermal aging at 750 °C for 13 h, the catalytic performance of Cu-ZSM-5-Aged catalyst was significantly reduced for NO reduction in the entire temperature range, while that of Cu-ZSM-5-CLD-Aged catalyst was affected very little. The characterization results indicated that an inert silica layer was deposited on the surface of Cu-ZSM-5 and formed a protective layer, which prevents the detachment of Cu2+ from ZSM-5 ion-exchange positions and the dealumination of zeolite during the hydrothermal aging process. Based on the data it is hypothesized to be the primary reason for the high hydrothermal stability of Cu-ZSM-5-CLD catalyst.

  17. Enhancement of Treatment Efficiency of Recalcitrant Wastewater Containing Textile Dyes Using a Newly Developed Iron Zeolite Socony Mobil-5 Heterogeneous Catalyst.

    PubMed

    Ahmad, Mushtaq; Asghar, Anam; Abdul Raman, Abdul Aziz; Wan Daud, Wan Mohd Ashri

    2015-01-01

    Fenton oxidation, an advanced oxidation process, is an efficient method for the treatment of recalcitrant wastewaters. Unfortunately, it utilizes H2O2 and iron-based homogeneous catalysts, which lead to the formation of high volumes of sludge and secondary pollutants. To overcome these problems, an alternate option is the usage of heterogeneous catalyst. In this study, a heterogeneous catalyst was developed to provide an alternative solution for homogeneous Fenton oxidation. Iron Zeolite Socony Mobile-5 (Fe-ZSM-5) was synthesized using a new two-step process. Next, the catalyst was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis and tested against a model wastewater containing the azo dye Acid Blue 113. Results showed that the loading of iron particles reduced the surface area of the catalyst from 293.59 to 243.93 m2/g; meanwhile, the average particle size of the loaded material was 12.29 nm. Furthermore, efficiency of the developed catalyst was evaluated by performing heterogeneous Fenton oxidation. Taguchi method was coupled with principal component analysis in order to assess and optimize mineralization efficiency. Experimental results showed that under optimized conditions, over 99.7% degradation and 77% mineralization was obtained, with a 90% reduction in the consumption of the developed catalyst. Furthermore, the developed catalyst was stable and reusable, with less than 2% leaching observed under optimized conditions. Thus, the present study proved that newly developed catalyst has enhanced the oxidation process and reduced the chemicals consumption.

  18. Enhancement of Treatment Efficiency of Recalcitrant Wastewater Containing Textile Dyes Using a Newly Developed Iron Zeolite Socony Mobil-5 Heterogeneous Catalyst

    PubMed Central

    Ahmad, Mushtaq; Asghar, Anam; Abdul Raman, Abdul Aziz; Wan Daud, Wan Mohd Ashri

    2015-01-01

    Fenton oxidation, an advanced oxidation process, is an efficient method for the treatment of recalcitrant wastewaters. Unfortunately, it utilizes H2O2 and iron-based homogeneous catalysts, which lead to the formation of high volumes of sludge and secondary pollutants. To overcome these problems, an alternate option is the usage of heterogeneous catalyst. In this study, a heterogeneous catalyst was developed to provide an alternative solution for homogeneous Fenton oxidation. Iron Zeolite Socony Mobile-5 (Fe-ZSM-5) was synthesized using a new two-step process. Next, the catalyst was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis and tested against a model wastewater containing the azo dye Acid Blue 113. Results showed that the loading of iron particles reduced the surface area of the catalyst from 293.59 to 243.93 m2/g; meanwhile, the average particle size of the loaded material was 12.29 nm. Furthermore, efficiency of the developed catalyst was evaluated by performing heterogeneous Fenton oxidation. Taguchi method was coupled with principal component analysis in order to assess and optimize mineralization efficiency. Experimental results showed that under optimized conditions, over 99.7% degradation and 77% mineralization was obtained, with a 90% reduction in the consumption of the developed catalyst. Furthermore, the developed catalyst was stable and reusable, with less than 2% leaching observed under optimized conditions. Thus, the present study proved that newly developed catalyst has enhanced the oxidation process and reduced the chemicals consumption. PMID:26517827

  19. Silver/iron oxide/graphitic carbon composites as bacteriostatic catalysts for enhancing oxygen reduction in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Ma, Ming; You, Shijie; Gong, Xiaobo; Dai, Ying; Zou, Jinlong; Fu, Honggang

    2015-06-01

    Biofilms from anode heterotrophic bacteria are inevitably formed over cathodic catalytic sites, limiting the performances of single-chamber microbial fuel cells (MFCs). Graphitic carbon (GC) - based nano silver/iron oxide (AgNPs/Fe3O4/GC) composites are prepared from waste pomelo skin and used as antibacterial oxygen reduction catalysts for MFCs. AgNPs and Fe3O4 are introduced in situ into the composites by one-step carbothermal reduction, enhancing their conductivity and catalytic activity. To investigate the effects of Fe species on the antibacterial and catalytic properties, AgNPs/Fe3O4/GC is washed with sulfuric acid (1 mol L-1) for 0.5 h, 1 h, and 5 h and marked as AgNPs/Fe3O4/GC-x (x = 0.5 h, 1 h and 5 h, respectively). A maximum power density of 1712 ± 35 mW m-2 is obtained by AgNPs/Fe3O4/GC-1 h, which declines by 4.12% after 17 cycles. Under catalysis of all AgNP-containing catalysts, oxygen reduction reaction (ORR) proceeds via the 4e- pathway, and no toxic effects to anode microorganisms result from inhibiting the cathodic biofilm overgrowth. With the exception of AgNPs/Fe3O4/GC-5 h, the AgNPs-containing composites exhibit remarkable power output and coulombic efficiency through lowering proton transfer resistance and air-cathode biofouling. This study provides a perspective for the practical application of MFCs using these efficient antibacterial ORR catalysts.

  20. From First Principles Design to Realization of Bimetallic Catalysts for Enhanced Selectivity

    SciTech Connect

    Lobo, Raul F.; Crooks, Richard M.; Mavrikakis, Manos

    2014-04-08

    “Catalysis by design” has been a dream for decades. To specify the composition and structure of matter to effect a desired catalytic transformation with desired and predicted rate and selectivity remains a monumental challenge, especially in heterogeneous catalysis. Our research thrusts have been chosen not only for their practical and scientific relevance, e.g. for more efficient and sustainable chemicals and fuels production, but also because they provide a foundation for developing and exploring broadly applicable principles and strategies for catalyst design.

  1. Enhanced Activity and Stability of Pt catalysts on Functionalized Graphene Sheets for Electrocatalytic Oxygen Reduction

    SciTech Connect

    Kou, Rong; Shao, Yuyan; Wang, Donghai; Engelhard, Mark H.; Kwak, Ja Hun; Wang, Jun; Viswanathan, Vilayanur V.; Wang, Chong M.; Lin, Yuehe; Wang, Yong; Aksay, Ilhan A.; Liu, Jun

    2009-04-30

    Electrocatalysis of oxygen reduction using Pt nanoparticles supported on functionalized graphene sheets (FGSs) was studied. FGSs were prepared by thermal expansion of graphite oxide. Pt nanoparticles with average diameter of 2 nm were uniformly loaded on FGSs by impregnation methods. Pt-FGS showed a higher electrochemical surface area and oxygen reduction activity with improved stability as compared with commercial catalyst. Transmission electron microscopy, X-ray photoelectron spectroscopy, and electrochemical characterization suggest that the improved performance of Pt-FGS can be attributed to smaller particle size and less aggregation of Pt nanoparticles on the functionalized graphene sheets.

  2. Optimized Blanching Reduces the Host Cell Protein Content and Substantially Enhances the Recovery and Stability of Two Plant-Derived Malaria Vaccine Candidates

    PubMed Central

    Menzel, Stephan; Holland, Tanja; Boes, Alexander; Spiegel, Holger; Bolzenius, Johanna; Fischer, Rainer; Buyel, Johannes F.

    2016-01-01

    Plants provide an advantageous expression platform for biopharmaceutical proteins because of their low pathogen burden and potential for inexpensive, large-scale production. However, the purification of target proteins can be challenging due to issues with extraction, the removal of host cell proteins (HCPs), and low expression levels. The heat treatment of crude extracts can reduce the quantity of HCPs by precipitation thus increasing the purity of the target protein and streamlining downstream purification. In the overall context of downstream process (DSP) development for plant-derived malaria vaccine candidates, we applied a design-of-experiments approach to enhance HCP precipitation from Nicotiana benthamiana extracts generated after transient expression, using temperatures in the 20–80°C range, pH values of 3.0–8.0 and incubation times of 0–60 min. We also investigated the recovery of two protein-based malaria vaccine candidates under these conditions and determined their stability in the heat-treated extract while it was maintained at room temperature for 24 h. The heat precipitation of HCPs was also carried out by blanching intact plants in water or buffer prior to extraction in a blender. Our data show that all the heat precipitation methods reduced the amount of HCP in the crude plant extracts by more than 80%, simplifying the subsequent DSP steps. Furthermore, when the heat treatment was performed at 80°C rather than 65°C, both malaria vaccine candidates were more stable after extraction and the recovery of both proteins increased by more than 30%. PMID:26925077

  3. Enhanced production of xylose from corncob hydrolysis with oxalic acid as catalyst.

    PubMed

    Jin, Li-Qun; Zhao, Nan; Liu, Zhi-Qiang; Liao, Cheng-Jun; Zheng, Xiao-Yang; Zheng, Yu-Guo

    2017-09-30

    The acid-catalyzed treatment was a conventional process for xylose production from corncob. To increase the release of xylose and to reduce the by-products formation and water usage, the oxalic acid was used as catalyst to hydrolyze the corncob and the hydrolytic conditions were investigated. The highest xylose yield of 32.7 g L(-1), representing 96.1% of total theoretical xylose yield, was obtained using 1.2% oxalic acid after hydrolysis for 120 min at 130 °C, which was more than 10% higher than that of sulfuric acid-catalyzed hydrolysis. Mixed acids-catalyzed hydrolysis performed a synergistic effect for xylose production and 31.7 g L(-1) of xylose was reached after reacting for 90 min with oxalic acid and sulfuric acid at a ratio of 1:4 (w/w). A kinetic model was developed to elucidate the competitive reaction between xylose formation and its degradation in the hydrolysis process, and the experimental data obtained in this study were perfectly in agreement with that of predicted from the model. Furthermore, the final xylose yield of 85% was achieved after purification and crystallization. It was demonstrated that xylose production from the corncob hydrolysis with oxalic acid as the catalyst was an effective alternative to the traditional sulfuric acid-based hydrolysis.

  4. Graphitic carbon nitride induced activity enhancement of OMS-2 catalyst for pollutants degradation with peroxymonosulfate

    NASA Astrophysics Data System (ADS)

    Li, Jun; Fang, Jia; Gao, Long; Zhang, Jingwen; Ruan, Xinchao; Xu, Aihua; Li, Xiaoxia

    2017-04-01

    Low valent manganese species and surface oxygen vacancies in OMS-2 play an important role in catalytic reactions, and it is highly desirable and challenging to develop a feasible strategy of increasing the Mn(II) and Mn(III) species concentration in the oxide. Herein, the OMS-2/g-C3N4 hybrids (OMS-2/CN) were prepared by a facile refluxing approach. It was found that the MnOx precursor from the reaction of KMnO4 and MnSO4 was transformed into OMS-2 nanofibers with the formation of more Mn(II) and Mn(III) species in OMS-2 and the destruction and oxidation of g-C3N4. The hybrids exhibited higher efficiency for pollutants degradation in the presence of PMS than the pure OMS-2 or g-C3N4. There was a linear correlation between the specific initial rate and the ratio of Mn(II + III)/Mn(IV). Mechanism investigation indicated that high active manganese species or caged radicals were produced through the oxidation of Mn(II) and Mn(III) by PMS and contributed to the degradation reaction. During five consecutive cycles, the catalyst exhibited good reusability and stability. Therefore, the OMS-2/CN hybrids are promising catalysts for wastewater treatment with PMS as the oxidant.

  5. Decomposition of triphenylborane with enhanced comprehensive catalyst under aerated and inert conditions

    SciTech Connect

    Wilmarth, W.R.; Crawford, C.L.; Peterson, R.A.; White, T.L.

    1997-09-30

    This work investigated the decomposition of triphenylborane in a statistically-designed set of tests to determine the effects of four process variables: temperature, hydroxide concentration, catalyst concentration, and atmosphere. Analysis of these tests provide the following conclusions:(1) The presence of tetraphenylborate solids facilitate a 10X increase in the rate of decomposition of triphenylborane, (2) The presence of oxygen slows the decomposition of triphenylborane, (3) The activation energy of the decomposition reaction in the presence of oxygen (59.88 + 27.73 kJ/mol) is statistically lower than inerted systems (99.11 + 10.14 kJ/mol), (4) Rate constants derived from the nitrogen inerted tests encompass the rate constants from previous tests with slurries. These rate constants agree reasonably with similar values obtained from Tank 48H operations at ambient temperatures, and (5) For test conducted in air, the decomposition reaction rate constant correlated with the catalyst concentration. In tests inerted by nitrogen, the same correlation did not hold.

  6. Enhanced hydrolysis of bamboo biomass by chitosan based solid acid catalyst with surfactant addition in ionic liquid.

    PubMed

    Si, Wenqing; Li, Yichen; Zheng, Jie; Wei, Shun'an; Wang, Dan

    2017-10-15

    Surfactants were used for the hydrolysis of bamboo biomass to enhance lignocellulose hydrolysis. Tween 80, polyethylene glycol 4000 (PEG 4000), and sodium dodecyl sulfate (SDS) were tested as surfactants for improving the bamboo hydrolysis with a novel sulfonated cross-linked chitosan solid acid catalyst (SCCAC) in ionic liquid (IL). Compared to the use of only SCCAC in 1-Butyl-3-methylimidazolium chloride ([BMIM]Cl), the surfactants facilitated hydrolysis and improved the yield of total reducing sugar (TRS) under the same conditions. Tween 80 was the most effective surfactant, with a TRS yield of 68.01% achieved at 120°C after 24h. Surfactants broke the lignocellulose structure, promoted lignin removal, and increased positive interactions between cellulose and the catalyst, which were favorable for hydrolysis. This novel surfactant-assisted hydrolysis strategy with SCCAC and IL as the solvent demonstrated a promise for the large-scale transformation of biomass into biofuels and bioproducts. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Enhancement in open-circuit voltage of implantable CMOS-compatible glucose fuel cell by improving the anodic catalyst

    NASA Astrophysics Data System (ADS)

    Niitsu, Kiichi; Ando, Takashi; Kobayashi, Atsuki; Nakazato, Kazuo

    2017-01-01

    This paper presents an implantable CMOS-compatible glucose fuel cell that generates an open-circuit voltage (OCV) of 880 mV. The developed fuel cell is solid-catalyst-based and manufactured from biocompatible materials; thus, it can be implanted to the human body. Additionally, since the cell can be manufactured using a semiconductor (CMOS) fabrication process, it can also be manufactured together with CMOS circuits on a single silicon wafer. In the literature, an implantable CMOS-compatible glucose fuel cell has been reported. However, its OCV is 192 mV, which is insufficient for CMOS circuit operation. In this work, we have enhanced the performance of the fuel cell by improving the electrocatalytic ability of the anode. The prototype with the newly proposed Pt/carbon nanotube (CNT) anode structure successfully achieved an OCV of 880 mV, which is the highest ever reported.

  8. Photo-enhanced activity of Pt and Pt-Ru catalysts towards the electro-oxidation of methanol

    NASA Astrophysics Data System (ADS)

    Arulmani, Dheevesh V.; Eastcott, Jennie I.; Mavilla, Stephanie G.; Easton, E. Bradley

    2014-02-01

    Electrocatalyst materials, consisting of Pt or Pt-Ru supported on carbon with and without TiO2, are evaluated for their activity towards the methanol oxidation reaction (MOR) in 1.0 M H2SO4 at 25 °C in the presence and absence of visible light irradiation. Electrochemical studies showed that enhanced MOR activity is achieved upon irradiation with visible light for each catalyst, in both the presence and absence of TiO2. Irradiation leads to no improvement in activity towards the formic acid oxidation reaction (FAOR) indicating that irradiation aids in the removal of adsorbed intermediate species, such as CO, during MOR. While the presence of a TiO2 support does lead to an increase in activity upon irradiation, about 50% of the improvements arise solely from the irradiation of the metal-containing electrocatalysts themselves.

  9. Water-assisted highly enhanced crystallographic etching of graphene by iron catalysts

    NASA Astrophysics Data System (ADS)

    Xue, Lei-Jiang; Yu, Fang; Zhou, Hai-Qing; Sun, Lian-Feng

    2015-03-01

    We report the assisted role of water vapor in crystallographic cutting of graphene via iron catalysts in reduced atmosphere. Without water, graphene can be tailored with smooth trenches composed of straight lines with angles of 60° or 120° between two adjacent trenches. After the addition of water, new chacteristics are found: such as almost no iron particles can be detected along the trenches; each trench becomes longer and lots of graphene nanoribbons can be generated. The underlying mechanism is proposed and discussed, which is attributed to stimulating and lengthening of the catalytic activity of iron particles by water vapor. Project supported by the National Natural Science Foundation of China (Grant No. 10774032) and the Instrument Developing Project of the Chinese Academy of Sciences (Grant No. Y2010031).

  10. Enhanced electrochemical oxidation of Acid Red 3R wastewater with iron phosphomolybdate supported catalyst.

    PubMed

    Wang, Li; Yue, Lin; Shi, Feng; Guo, Jianbo; Yang, Jingliang; Lian, Jing; Luo, Xiao; Guo, Yankai

    2015-01-01

    Electrochemical oxidation of Acid Red 3R (AR3R) was investigated with the new catalyst of iron phosphomolybdate (FePMo12) supported on modified molecular sieves type 4 Å (4A) as packing materials in the reactor. The results of the Fourier transform infrared spectroscopy and X-ray diffraction indicated that the heteropolyanion had a Keggin structure. The optimal conditions for decolorization of simulated AR3R wastewater were as follows: current density 35 mA/cm², initial pH 4.0, airflow 0.08 m³/hour and inter-electrode distance 3.0 cm. With the addition of NaCl to the system, the decolorization efficiency increased. But Na₂SO₄had a negative effect on the decolorization efficiency, which was attributed to the negative salt effect. The degradation mechanisms of AR3R were also discussed in detail.

  11. Catalyst free growth of ZnO nanowires on graphene and graphene oxide and its enhanced photoluminescence and photoresponse

    NASA Astrophysics Data System (ADS)

    Biroju, Ravi K.; Tilak, Nikhil; Rajender, Gone; Dhara, S.; Giri, P. K.

    2015-04-01

    We demonstrate the graphene assisted catalyst free growth of ZnO nanowires (NWs) on chemical vapor deposited (CVD) and chemically processed graphene buffer layers at a relatively low growth temperature (580 °C) in the presence and absence of ZnO seed layers. In the case of CVD graphene covered with rapid thermal annealed ZnO buffer layer, the growth of vertically aligned ZnO NWs takes place, while the direct growth on CVD graphene, chemically derived graphene (graphene oxide and graphene quantum dots) without ZnO seed layer resulted in randomly oriented sparse ZnO NWs. Growth mechanism was studied from high resolution transmission electron microscopy and Raman spectroscopy of the hybrid structure. Further, we demonstrate strong UV, visible photoluminescence (PL) and enhanced photoconductivity (PC) from the CVD graphene-ZnO NWs hybrids as compared to the ZnO NWs grown without the graphene buffer layer. The evolution of crystalinity in ZnO NWs grown with ZnO seed layer and graphene buffer layer is correlated with the Gaussian line shape of UV and visible PL. This is further supported by the strong Raman mode at 438 cm-1 significant for the wurtzite phase of the ZnO NWs grown on different graphene substrates. The effect of the thickness of ZnO seed layers and the role of graphene buffer layers on the aligned growth of ZnO NWs and its enhanced PC are investigated systematically. Our results demonstrate the catalyst free growth and superior performance of graphene-ZnO NW hybrid UV photodetectors as compared to the bare ZnO NW based photodetectors.

  12. Enhanced electrochemical methanation of carbon dioxide with a dispersible nanoscale copper catalyst.

    PubMed

    Manthiram, Karthish; Beberwyck, Brandon J; Alivisatos, A Paul

    2014-09-24

    Although the vast majority of hydrocarbon fuels and products are presently derived from petroleum, there is much interest in the development of routes for synthesizing these same products by hydrogenating CO2. The simplest hydrocarbon target is methane, which can utilize existing infrastructure for natural gas storage, distribution, and consumption. Electrochemical methods for methanizing CO2 currently suffer from a combination of low activities and poor selectivities. We demonstrate that copper nanoparticles supported on glassy carbon (n-Cu/C) achieve up to 4 times greater methanation current densities compared to high-purity copper foil electrodes. The n-Cu/C electrocatalyst also exhibits an average Faradaic efficiency for methanation of 80% during extended electrolysis, the highest Faradaic efficiency for room-temperature methanation reported to date. We find that the level of copper catalyst loading on the glassy carbon support has an enormous impact on the morphology of the copper under catalytic conditions and the resulting Faradaic efficiency for methane. The improved activity and Faradaic efficiency for methanation involves a mechanism that is distinct from what is generally thought to occur on copper foils. Electrochemical data indicate that the early steps of methanation on n-Cu/C involve a pre-equilibrium one-electron transfer to CO2 to form an adsorbed radical, followed by a rate-limiting non-electrochemical step in which the adsorbed CO2 radical reacts with a second CO2 molecule from solution. These nanoscale copper electrocatalysts represent a first step toward the preparation of practical methanation catalysts that can be incorporated into membrane-electrode assemblies in electrolyzers.

  13. Enhanced Interfacial Charge Transfer on a Tungsten Trioxide Photoanode with Immobilized Molecular Iridium Catalyst.

    PubMed

    Tong, Haili; Jiang, Yi; Zhang, Qian; Li, Jialing; Jiang, Wenchao; Zhang, Donghui; Li, Na; Xia, Lixin

    2017-08-24

    The rational design of active photoanodes for photoelectrochemical (PEC) water splitting is crucial for future applications in sustainable energy conversion. A combination of catalysts with photoelectrodes is generally required to improve surface kinetics and suppress surface recombination. In this study, we present WO3 photoanode modified with the iridium complex [(H4 dphbpy)Ir(III) (Cp*)Cl]Cl (Ir-PO3 H2 ; H4 dphbpy=2,2'-bipyridine-4,4'-bisphosphonic acid, Cp*=pentamethylcyclopentadiene (WO3 +Ir-PO3 H2 )- for PEC water oxidation. When Ir-PO3 H2 is anchored to a WO3 electrode, the photoanode shows a significant improvement in both photocurrent and faradaic efficiency compared to the bare WO3 photoanode. Under simulated sunlight illumination (AM 1.5G, 100 mW cm(-2) ) with an applied bias of 1.23 V (vs. reversible hydrogen electrode), the photoanode exhibits a photocurrent of 1.16 mA cm(-2) in acidic conditions, which is double that of the bare WO3 photoanode. The faradaic efficiency is promoted from 56 % to 95 %. Kinetic studies reveal that Ir-PO3 H2 exhibits a different interfacial charge-transfer mechanism on the WO3 photoanode for PEC water oxidation compared to iridium oxide. Ir-PO3 H2 , as a water-oxidation catalyst, can accelerate the surface charge transfer through rapid surface kinetics. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. The role of KCl in FeCl3-KCl/Al2O3 catalysts with enhanced catalytic performance for ethane oxychlorination.

    PubMed

    Zhou, Qihua; Hu, Ruisheng; Jia, Yun; Wang, Hongye

    2017-08-08

    Among the vinyl chloride production processes, ethane oxychlorination is the most economical and environment-friendly process but constrained by the lack of high performance catalysts for industrial applications. In this work, FeCl3-KCl/Al2O3 catalysts with different molar ratios of K/Fe were prepared by a co-impregnation method and applied to ethane oxychlorination. The FeCl3-KCl/Al2O3 catalyst with K/Fe = 2 exhibited enhanced catalytic performance with the highest conversion of C2H6 (99.1%) and the best selectivity to C2H3Cl (74%) under the optimal conditions of 400 °C, C2H6 : HCl : air = 1 : 3 : 5.5 (volume ratio) and GHSV = 4560 h(-1). It was found that the enhanced catalytic performance could be attributed to the formation of KFeCl4 from KCl and FeCl3 and the change of the reaction process. Besides, KCl is in favor of weakening the interaction between the active species and support. The reduction activation energy of Fe(iii) → Fe(ii) is efficiently reduced by KCl addition. The FeCl3-KCl/Al2O3 catalyst may be a potential catalyst for industry due to its simple composition and convenient preparation.

  15. Interaction between Ni and HZSM-5 in aromatization-enhanced reactive adsorption desulfurization catalysts for FCC gasoline upgrading.

    PubMed

    Zhao, Jinchong; Zhang, Lulu; She, Nannan; Liu, Yunqi; Chai, Yongming; Liu, Chenguang

    A compound catalyst (RA) consisted of Ni, ZnO and HZSM-5 with functions of reactive adsorption desulfurization (RADS) and olefin aromatization for fluid catalytic cracking (FCC) gasoline upgrading was prepared. X-ray powder diffraction (XRD), temperature-programmed reduction and low-temperature N2 adsorption were used to characterize the properties of the catalysts. Performance evaluation by FCC gasoline was carried out, and the result showed that the catalyst RA performed well in desulfurization and aromatization. For comparison, RADS catalyst (represented by DS) consisted of Ni and ZnO and aromatization catalyst (represented by Ar) consisted of HZSM-5 were prepared, respectively. They were combined in different ways to help investigating interaction between Ni and HZSM-5. Performance evaluated by FCC gasoline showed that catalyst RA performed best in desulfurization with a slight octane number loss. Interaction between Ni and HZSM-5 is a significant factor which influences the performance of the catalyst.

  16. Pore development in carbonized hemoglobin by concurrently generated MgO template for activity enhancement as fuel cell cathode catalyst.

    PubMed

    Maruyama, Jun; Hasegawa, Takahiro; Amano, Taiji; Muramatsu, Yasuji; Gullikson, Eric M; Orikasa, Yuki; Uchimoto, Yoshiharu

    2011-12-01

    Various carbon materials with a characteristic morphology and pore structure have been produced using template methods in which a carbon-template composite is once formed and the characteristic features derived from the template are generated after the template removal. In this study, hemoglobin, which is a natural compound that could be abundantly and inexpensively obtained, was used as the carbon material source to produce a carbonaceous noble-metal-free fuel cell cathode catalyst. Magnesium oxide was used as the template concurrently generated with the hemoglobin carbonization from magnesium acetate mixed with hemoglobin as the starting material mixture to enable pore development for improving the activity of the carbonized hemoglobin for the cathodic oxygen reduction. After removal of the MgO template, the substantially developed pores were generated in the carbonized hemoglobin with an amorphous structure observed by total-electron-yield X-ray absorption. The extended X-ray absorption fine structure at the Fe-K edge indicated that Fe was coordinated with four nitrogen atoms (Fe-N(4) moiety) in the carbonized hemoglobin. The oxygen reduction activity of the carbonized hemoglobin evaluated using rotating disk electrodes was dependent on the pore structure. The highly developed pores led to an improved activity.

  17. Amperometric S-nitrosothiol sensor with enhanced sensitivity based on organoselenium catalysts.

    PubMed

    Cha, Wansik; Anderson, Meredith R; Zhang, Fenghua; Meyerhoff, Mark E

    2009-04-15

    A new S-nitrosothiol (RSNO) detection strategy based on an electrochemical sensor is described for rapidly estimating levels of total RSNOs in blood and other biological samples. The sensor employs a cellulose dialysis membrane covalently modified with an organoselenium catalyst that converts RSNOs to NO at the distal tip of an amperometric NO sensor. The sensor is characterized by very low detection limits (<20 nM), good long-term stability, and can be employed for the rapid detection of total low-molecular-weight (LMW) RSNO levels in whole blood samples using a simple standard addition method. A strategy for detecting macromolecular RSNOs is also demonstrated via use of a transnitrosation reaction with added LMW thiols allowing the estimation of total RSNO levels in blood. The sensor is shown to exhibit high selectivity over nitrosamines and nitrite. Such RSNO detection is potentially useful to reveal correlation between blood RSNO levels and endothelial cell dysfunction, which often is associated with cardiovascular diseases.

  18. Mobilizing Community Resources to Enhance Postdischarge Support for Breastfeeding in Massachusetts (USA): Results of a Catalyst Grant Approach.

    PubMed

    Colchamiro, Rachel; Edwards, Roger A; Nordstrom, Christina; Eshelman, Jill; Ghiringhelli, Kara; Forgit, Julie; Tolan, Ellen; Mainello, Kristen; Foley, Judi

    2015-11-01

    The Massachusetts Department of Public Health's (MDPH) Mass in Motion Program (MiM) facilitates the adoption of community-level strategies that promote healthy weight in 52 municipalities. MiM provided the platform for enhancing postdischarge continuity of care for breastfeeding. This study aimed to improve the continuity of breastfeeding care and support for mothers by enhancing postdischarge care infrastructure and supportive contacts for women and families. The MDPH awarded catalyst grants to community-based organizations (CBOs) that facilitated the formation of teams for improving breastfeeding support. The effort focused on populations that often experience disparities in breastfeeding outcomes such as minority women and women receiving Medicaid. The Added Value Model of Community Coalitions was used to qualitatively assess effect across multiple levels of the socioecological model of influence. Six communities were awarded grants to enhance or convene Breastfeeding Continuity-of-Care Teams consisting of at least 3 CBOs, including 1 maternity hospital, the local Special Supplemental Nutrition Program for Women, Infants, and Children, and the local MiM representative. Teams implemented customized plans with performance indicators to create and strengthen infrastructure for supportive contacts with breastfeeding mothers. The project included Baby Café pilots in 3 additional MiM communities. Across all grantee communities, there was an average total increase of 491 contacts with mothers per month, an improvement of 8.5% over baseline. The project created 153 added value outcomes of community collaboration at 5 levels in the socioecological framework. The project demonstrated how cross-sector, coordinated efforts focused on vulnerable populations can leverage local strengths to establish/enhance breastfeeding support services customized to local needs. © The Author(s) 2015.

  19. Synchrotron high energy X-ray methods coupled to phase sensitive analysis to characterize aging of solid catalysts with enhanced sensitivity.

    PubMed

    Ferri, Davide; Newton, Mark A; Di Michiel, Marco; Yoon, Songhak; Chiarello, Gian Luca; Marchionni, Valentina; Matam, Santhosh Kumar; Aguirre, Myriam H; Weidenkaff, Anke; Wen, Fei; Gieshoff, Jürgen

    2013-06-14

    X-ray absorption spectroscopy and X-ray diffraction are suitable probes of the chemical state of a catalyst under working conditions but are limited to bulk information. Here we show in two case studies related to hydrothermal aging and chemical modification of model automotive catalysts that enhanced detailed information of structural changes can be obtained when the two methods are combined with a concentration modulated excitation (cME) approach and phase sensitive detection (PSD). The catalysts are subject to a modulation experiment consisting of the periodic variation of the gas feed composition to the catalyst and the time-resolved data are additionally treated by PSD. In the case of a 2 wt% Rh/Al2O3 catalyst, a very small fraction (ca. 2%) of Rh remaining exposed at the alumina surface after hydrothermal aging at 1273 K can be detected by PSD. This Rh is sensitive to the red-ox oscillations of the experiment and is likely responsible for the observed catalytic activity and selectivity during NO reduction by CO. In the case of a 1.6 wt% Pd/Al2O3-Ce(1-x)Zr(x)O2 catalyst, preliminary results of cME-XRD demonstrate that access to the kinetics of the whole material at work can be obtained. Both the red-ox processes involving the oxygen storage support and the Pd component can be followed with great precision. PSD enables the differentiation between Pd deposited on Al2O3 or on Ce(1-x)Zr(x)O2. Modification of the catalyst by phosphorous clearly induces loss of the structural dynamics required for oxygen storage capacity that is provided by the Ce(4+)/Ce(3+) pair. The two case studies demonstrate that detailed kinetics of subtle changes can be uncovered by the combination of in situ X-ray absorption and high energy diffraction methods with PSD.

  20. A New Bioinspired Perchlorate Reduction Catalyst with Significantly Enhanced Stability via Rational Tuning of Rhenium Coordination Chemistry and Heterogeneous Reaction Pathway.

    PubMed

    Liu, Jinyong; Han, Mengwei; Wu, Dimao; Chen, Xi; Choe, Jong Kwon; Werth, Charles J; Strathmann, Timothy J

    2016-06-07

    Rapid reduction of aqueous ClO4(-) to Cl(-) by H2 has been realized by a heterogeneous Re(hoz)2-Pd/C catalyst integrating Re(O)(hoz)2Cl complex (hoz = oxazolinyl-phenolato bidentate ligand) and Pd nanoparticles on carbon support, but ClOx(-) intermediates formed during reactions with concentrated ClO4(-) promote irreversible Re complex decomposition and catalyst deactivation. The original catalyst design mimics the microbial ClO4(-) reductase, which integrates Mo(MGD)2 complex (MGD = molybdopterin guanine dinucleotide) for oxygen atom transfer (OAT). Perchlorate-reducing microorganisms employ a separate enzyme, chlorite dismutase, to prevent accumulation of the destructive ClO2(-) intermediate. The structural intricacy of MGD ligand and the two-enzyme mechanism for microbial ClO4(-) reduction inspired us to improve catalyst stability by rationally tuning Re ligand structure and adding a ClOx(-) scavenger. Two new Re complexes, Re(O)(htz)2Cl and Re(O)(hoz)(htz)Cl (htz = thiazolinyl-phenolato bidentate ligand), significantly mitigate Re complex decomposition by slightly lowering the OAT activity when immobilized in Pd/C. Further stability enhancement is then obtained by switching the nanoparticles from Pd to Rh, which exhibits high reactivity with ClOx(-) intermediates and thus prevents their deactivating reaction with the Re complex. Compared to Re(hoz)2-Pd/C, the new Re(hoz)(htz)-Rh/C catalyst exhibits similar ClO4(-) reduction activity but superior stability, evidenced by a decrease of Re leaching from 37% to 0.25% and stability of surface Re speciation following the treatment of a concentrated "challenge" solution containing 1000 ppm of ClO4(-). This work demonstrates the pivotal roles of coordination chemistry control and tuning of individual catalyst components for achieving both high activity and stability in environmental catalyst applications.

  1. Enhanced Dry Reforming of Methane on Ni and Ni-Pt Catalysts Synthesized by Atomic Layer Deposition

    SciTech Connect

    Gould, Troy D.; Montemore, Matthew M.; Lubers, Alia M.; Ellis, Lucas D.; Weimer, Alan; Falconer, John L.; Medlin, James W.

    2015-02-25

    Atomic layer deposition (ALD) was used to deposit Ni and Pt on alumina supports to form monometallic and bimetallic catalysts with initial particle sizes of 1–2.4 nm. The ALD catalysts were more active (per mass of metal) than catalysts prepared by incipient wetness (IW) for dry reforming of methane (DRM), and they did not form carbon whiskers during reaction due to their sufficiently small size. Catalysts modified by Pt ALD had higher rates of reaction per mass of metal and inhibited coking, whereas NiPt catalysts synthesized by IW still formed carbon whiskers. Temperature-programmed reduction of Ni catalysts modified by Pt ALD indicated the presence of bimetallic interaction. Density functional theory calculations suggested that under reaction conditions, the NiPt surfaces form Ni-terminated surfaces that are associated with higher DRM rates (due to their C and O adsorption energies, as well as the CO formation and CH4 dissociation energies).

  2. Enhancement of biodiesel synthesis from soybean oil by potassium fluoride modification of a calcium magnesium oxides catalyst.

    PubMed

    Fan, Mingming; Zhang, Pingbo; Ma, Qinke

    2012-01-01

    Transesterification of soybean oil with methanol was carried out in the presence of CaO-MgO and KF-modified CaO-MgO catalysts at atmospheric pressure. While the methyl ester yield for the CaO-MgO catalyst with a ratio of 8:2 (CaO:MgO) was 63.6%, it was 97.9% for the KF-modified catalyst at a 2% catalyst to the reactants (methanol/oil mixture) weight ratio, a temperature of 65 °C, a methanol-soybean oil ratio of 9:1 and a reaction time of 2.5 h. The KF/CaO-MgO catalyst still yielded 86.7% after four successive uses. The catalytic performance of the KF/CaO-MgO catalyst was attributed to the formation of active KCaF(3) and K(2)MgF(4) centers.

  3. Nanofiltration of rhodium tris(triphenylphosphine) catalyst in ethyl acetate solution

    NASA Astrophysics Data System (ADS)

    Shaharun, Maizatul S.; Mustafa, Ahmad K.; Taha, Mohd F.

    2012-09-01

    Solvent resistant nanofiltration (SRNF) using polymer membranes has recently received enhanced attention due to the search for cleaner and more energy-efficient technologies. The large size of the rhodium tris(triphenylphosphine) [HRh(CO)(PPh3)3] catalyst (>400 Da) - relative to other components of the hydroformylation reaction provides the opportunity for a membrane separation based on retention of the catalyst species while permeating the solvent. The compatibility of the solvent-polyimide membrane (DuraMem{trade mark, serif} 200 and DuraMem{trade mark, serif} 500) combinations was assessed in terms of the membrane stability in solvent plus non-zero solvent flux at 2.0 MPa. Good HRh(CO)(PPh3)3 rejection (>0.95) and solvent fluxes of 9.9 L/m2ṡh1 at 2.0 MPa were obtained in the catalyst-ethyl acetate-DuraMem 500 system. The effect of pressure and catalyst concentration on the solvent flux and catalyst rejection was conducted on the catalyst-ethyl acetate-membrane systems. Increasing pressure substantially improved both solvent flux and catalyst rejection, while increasing catalyst concentration was found to be beneficial in terms of substantial increases in catalyst rejection without significantly affecting solvent flux.

  4. Enhancement of Biodiesel Production from Marine Alga, Scenedesmus sp. through In Situ Transesterification Process Associated with Acidic Catalyst

    PubMed Central

    Kim, Ga Vin; Choi, WoonYong; Kang, DoHyung; Lee, ShinYoung; Lee, HyeonYong

    2014-01-01

    The aim of this study was to increase the yield of biodiesel produced by Scenedesmus sp. through in situ transesterification by optimizing various process parameters. Based on the orthogonal matrix analysis for the acidic catalyst, the effects of the factors decreased in the order of reaction temperature (47.5%) > solvent quantity (26.7%) > reaction time (17.5%) > catalyst amount (8.3%). Based on a Taguchi analysis, the effects of the factors decreased in the order of solvent ratio (34.36%) > catalyst (28.62%) > time (19.72%) > temperature (17.32%). The overall biodiesel production appeared to be better using NaOH as an alkaline catalyst rather than using H2SO4 in an acidic process, at 55.07 ± 2.18% (based on lipid weight) versus 48.41 ± 0.21%. However, in considering the purified biodiesel, it was found that the acidic catalyst was approximately 2.5 times more efficient than the alkaline catalyst under the following optimal conditions: temperature of 70°C (level 2), reaction time of 10 hrs (level 2), catalyst amount of 5% (level 3), and biomass to solvent ratio of 1 : 15 (level 2), respectively. These results clearly demonstrated that the acidic solvent, which combined oil extraction with in situ transesterification, was an effective catalyst for the production of high-quantity, high-quality biodiesel from a Scenedesmus sp. PMID:24689039

  5. Catalytically Enhanced Hydrogen Sorption in Mg-MgH2 by Coupling Vanadium-Based Catalyst and Carbon Nanotubes

    PubMed Central

    Kadri, Atikah; Jia, Yi; Chen, Zhigang; Yao, Xiangdong

    2015-01-01

    Mg (MgH2)-based composites, using carbon nanotubes (CNTs) and pre-synthesized vanadium-based complex (VCat) as the catalysts, were prepared by high-energy ball milling technique. The synergistic effect of coupling CNTs and VCat in MgH2 was observed for an ultra-fast absorption rate of 6.50 wt. % of hydrogen per minute and 6.50 wt. % of hydrogen release in 10 min at 200 °C and 300 °C, respectively. The temperature programmed desorption (TPD) results reveal that coupling VCat and CNTs reduces both peak and onset temperatures by more than 60 °C and 114 °C, respectively. In addition, the presence of both VCat and CNTs reduces the enthalpy and entropy of desorption of about 7 kJ/mol H2 and 11 J/mol H2·K, respectively, as compared to those of the commercial MgH2, which ascribe to the decrease of desorption temperature. From the study of the effect of CNTs milling time, it is shown that partially destroyed CNTs (shorter milling time) are better to enhance the hydrogen sorption performance.

  6. Enhancing the available specific surface area of carbon supports to boost the electroactivity of nanostructured Pt catalysts.

    PubMed

    Holade, Yaovi; Morais, Claudia; Servat, Karine; Napporn, Teko W; Kokoh, K Boniface

    2014-12-14

    We report increasing improvements in the available specific surface area of the commonly used Vulcan XC 72R and Ketjenblack EC-600JD carbons by simple thermal pre-treatment. The treated Vulcan and Ketjenblack substrates have a specific surface area of 322 and 1631 m(2) g(-1), respectively, instead of 262 and 1102 m(2) g(-1) for the as-received materials, which is a 23 and 48% improvement. Subsequently, when used as platinum nanoparticle (3 nm) supports, the electrochemical active surface area is enhanced by factors of 2.2 and 1.2 for treated Vulcan and Ketjenblack carbons, respectively. Furthermore, electrochemical investigations have highlighted a surprisingly improved catalytic activity for the pre-treated Vulcan XC 72R and Ketjenblack EC-600JD supported Pt nanoparticles. In fact, the synthesized nanostructures from the so-called "Bromide Anion Exchange" method exhibit good catalytic activity toward glucose electrooxidation, both in the alkaline medium and the phosphate buffered solution at pH 7.4. More importantly, the present catalysts are four times more active than those in the literature prepared under similar conditions for glucose dehydrogenation at low potential (0.27 V vs. Reversible Hydrogen Electrode). Consequently, these remarkable trends uncovered herein provide ample new strategic routes for the pre-treatment of Vulcan XC 72R and Ketjenblack carbons for widespread uses.

  7. Substantial enhancement in intrinsic coercivity on M-type strontium hexaferrite through the increase in magneto-crystalline anisotropy by co-doping of group-V and alkali elements

    SciTech Connect

    Ahn, Kyunghan Ryu, Byungki; Korolev, Dmitry; Jae Kang, Young

    2013-12-09

    The effect of d{sup 1} impurity doping in Sr-hexaferrite (SrM) on the magnetic anisotropy is investigated. First-principles calculations revealed that group-V elements (V, Nb) are stabilized with co-doping of alkali elements. Na{sup 1+}/K{sup 1+} doping at Sr{sup 2+}-site is found to be critical to form the d{sup 1} impurities at Fe-site. Experimentally, Na–V doped SrM shows the intrinsic coercivity of ∼5.4 kOe, which is ∼300% enhancement compared to undoped SrM and comparable value to La–Co co-doped SrM. Finally, the spin-orbit coupling from non-vanishing angular momentum of d{sup 1} impurity in SrM should be a main factor for such a substantial improvement of intrinsic coercivity.

  8. Process of making supported catalyst

    DOEpatents

    Schwarz, James A.; Subramanian, Somasundaram

    1992-01-01

    Oxide supported metal catalysts have an additional metal present in intimate association with the metal catalyst to enhance catalytic activity. In a preferred mode, iridium or another Group VIII metal catalyst is supported on a titania, alumina, tungsten oxide, silica, or composite oxide support. Aluminum ions are readsorbed onto the support and catalyst, and reduced during calcination. The aluminum can be added as aluminum nitrate to the iridium impregnate solution, e.g. chloroiridic acid.

  9. Atomic Layer-by-Layer Deposition of Platinum on Palladium Octahedra for Enhanced Catalysts toward the Oxygen Reduction Reaction

    DOE PAGES

    Park, Jinho; Zhang, Lei; Choi, Sang-Il; ...

    2015-02-08

    We systematically evaluated two different approaches to the syntheses of Pd@PtnL (n = 2–5) core–shell octahedra. We initially prepared the core–shell octahedra using a polyol-based route by titrating a Pt(IV) precursor into the growth solution containing Pd octahedral seeds at 200 °C through the use of a syringe pump. The number of Pt atomic layers could be precisely controlled from two to five by increasing the volume of the precursor solution while fixing the amount of seeds. We then demonstrated the synthesis of Pd@PtnL octahedra using a water-based route at 95 °C through the one-shot injection of a Pt(II) precursor.more » Due to the large difference in reaction temperature, the Pd@PtnL octahedra obtained via the water-based route showed sharper corners than their counterparts obtained through the polyol-based route. When compared to a commercial Pt/C catalyst based upon 3.2 nm Pt particles, the Pd@PtnL octahedra prepared using both methods showed similar remarkable enhancement in terms of activity (both specific and mass) and durability toward the oxygen reduction reaction. These calculations based upon periodic, self-consistent density functional theory suggested that the enhancement in specific activity for the Pd@PtnL octahedra could be attributed to the destabilization of OH on their PtnL*/Pd(111) surface relative to the {111} and {100} facets exposed on the surface of Pt/C. Finally. the destabilization of OH facilitates its hydrogenation, which was found to be the rate-limiting step of the oxygen reduction reaction on all these surfaces.« less

  10. Atomic Layer-by-Layer Deposition of Platinum on Palladium Octahedra for Enhanced Catalysts toward the Oxygen Reduction Reaction

    SciTech Connect

    Park, Jinho; Zhang, Lei; Choi, Sang-Il; Roling, Luke T.; Lu, Ning; Herron, Jeffrey A.; Xie, Shuifen; Wang, Jinguo; Kim, Moon J.; Mavrikakis, Manos; Xia, Younan

    2015-02-08

    We systematically evaluated two different approaches to the syntheses of Pd@PtnL (n = 2–5) core–shell octahedra. We initially prepared the core–shell octahedra using a polyol-based route by titrating a Pt(IV) precursor into the growth solution containing Pd octahedral seeds at 200 °C through the use of a syringe pump. The number of Pt atomic layers could be precisely controlled from two to five by increasing the volume of the precursor solution while fixing the amount of seeds. We then demonstrated the synthesis of Pd@PtnL octahedra using a water-based route at 95 °C through the one-shot injection of a Pt(II) precursor. Due to the large difference in reaction temperature, the Pd@PtnL octahedra obtained via the water-based route showed sharper corners than their counterparts obtained through the polyol-based route. When compared to a commercial Pt/C catalyst based upon 3.2 nm Pt particles, the Pd@PtnL octahedra prepared using both methods showed similar remarkable enhancement in terms of activity (both specific and mass) and durability toward the oxygen reduction reaction. These calculations based upon periodic, self-consistent density functional theory suggested that the enhancement in specific activity for the Pd@PtnL octahedra could be attributed to the destabilization of OH on their PtnL*/Pd(111) surface relative to the {111} and {100} facets exposed on the surface of Pt/C. Finally. the destabilization of OH facilitates its hydrogenation, which was found to be the rate-limiting step of the oxygen reduction reaction on all these surfaces.

  11. Visible-light-driven CO2 reduction with carbon nitride: enhancing the activity of ruthenium catalysts.

    PubMed

    Kuriki, Ryo; Sekizawa, Keita; Ishitani, Osamu; Maeda, Kazuhiko

    2015-02-16

    A heterogeneous photocatalyst system that consists of a ruthenium complex and carbon nitride (C3N4), which act as the catalytic and light-harvesting units, respectively, was developed for the reduction of CO2 into formic acid. Promoting the injection of electrons from C3N4 into the ruthenium unit as well as strengthening the electronic interactions between the two units enhanced its activity. The use of a suitable solvent further improved the performance, resulting in a turnover number of greater than 1000 and an apparent quantum yield of 5.7% at 400 nm. These are the best values that have been reported for heterogeneous photocatalysts for CO2 reduction under visible-light irradiation to date. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. 3D MoS2-graphene hybrid aerogels as catalyst for enhanced efficient hydrogen evolution

    NASA Astrophysics Data System (ADS)

    Xu, Xiaobing; Sun, Yuan; Qiao, Wen; Zhang, Xing; Chen, Xing; Song, Xueyin; Wu, Liqian; Zhong, Wei; Du, Youwei

    2017-02-01

    Aerogel composite materials consisting of MoS2 and reduced graphite oxide (rGO) are synthesized by a facile general hydrothermal method, where GO is utilized as a template and provides a novel substrate for the nucleation and subsequent growth of MoS2. These MoS2/rGO hybrid nanostructures exhibit three-dimensional (3D) leaf-like morphology, and show excellent electrocatalytic activities of hydrogen evolution reaction (HER), with a low overpotential of approximately 105 mV, a small Tafel slope of 51 mV/dec and a large exchange current density (j0) of 3.28 × 10-5 A/cm2. The superior electrochemical performance should be attributed to the 3D porous MoS2/rGO hybrid architecture, which enhances the conductivity from graphene to MoS2 as well as the HER activity.

  13. Post-Treatments for Multifunctional Property Enhancement of Carbon Nanotube Fibers from the Floating Catalyst Method.

    PubMed

    Tran, Thang Q; Fan, Zeng; Mikhalchan, Anastasiia; Liu, Peng; Duong, Hai M

    2016-03-01

    We investigated the effects of the synthesis conditions and condensation processes on the chemical compositions and multifunctional performance of the directly spun carbon nanotube (CNT) fibers. On the basis of the optimized synthesis conditions, a two-step post-treatment technique which involved acidification and epoxy infiltration was also developed to further enhance their mechanical and electrical properties. As a result, their tensile strength and Young's modulus increased remarkably by 177% and 325%, respectively, while their electrical conductivity also reached 8235 S/cm. This work may provide a general strategy for the postprocessing optimization of the directly spun CNT fibers. The treated CNT fibers with superior properties are promising for a wide range of applications, such as structural reinforcements and lightweight electric cables.

  14. Catalyst/cocatalyst nuclearity effects in single-site olefin polymerization. Significantly enhanced 1-octene and isobutene comonomer enchainment in ethylene polymerizations mediated by binuclear catalysts and cocatalysts.

    PubMed

    Li, Hongbo; Li, Liting; Marks, Tobin J; Liable-Sands, Louise; Rheingold, Arnold L

    2003-09-10

    This Communication describes the implementation of a new binuclear homometallic organotitanium "constrained geometry catalyst" (CGC), (mu-CH2CH2-3,3'){ (eta5-indenyl )[1-Me2Si (tBuN)](TiMe2)}2[EBICGC(TiMe2)2; Ti2], together with the bifunctional activators (Ph3C+)2[1,4-(C6F5)3BC6F4B(C6F5)3]2- (B2) and new bisborane 1,4-(C6F5)2BC6F4B(C6F5)2 (BN2) in ethylene + alpha-olefin copolymerization processes. Specifically examined are the comonomers 1-octene and poorly responsive isobutene. Large increases in comonomer enchainment efficiency into the polyethylene microstructure are observed versus the corresponding mononuclear catalyst [1-Me2Si(3-ethylindenyl)(tBuN)]TiMe2 (Ti1) + Ph3C+B(C6F5)4- (B1) or B(C6F5)3 (BN) under identical polymerization conditions. In ethylene + 1-octene copolymerization, 11 times more 1-octene incorporation is observed for Ti2 + B2 vs Ti1 + B1. In ethylene + isobutene copolymerization, 5 times more isobutene incorporation is observed for Ti2 + BN2 vs Ti1 + BN.

  15. Atomic Layer-by-Layer Deposition of Pt on Pd Nanocubes for Catalysts with Enhanced Activity and Durability toward Oxygen Reduction

    SciTech Connect

    Xie, Shuifen; Choi, Sang -Il; Lu, Ning; Roling, Luke T.; Herron, Jeffrey A.; Zhang, Lei; Park, Jinho; Wang, Jinguo; Kim, Moon J.; Xie, Zhaoxiong; Mavrikakis, Manos; Xia, Younan

    2014-05-05

    Here, an effective strategy for reducing the Pt content while retaining the activity of a Pt-based catalyst is to deposit the Pt atoms as ultrathin skins of only a few atomic layers thick on nanoscale substrates made of another metal. During deposition, however, the Pt atoms often take an island growth mode because of a strong bonding between Pt atoms. Here we report a versatile route to the conformal deposition of Pt as uniform, ultrathin shells on Pd nanocubes in a solution phase. The introduction of the Pt precursor at a relatively slow rate and high temperature allowed the deposited Pt atoms to spread across the entire surface of a Pd nanocube to generate a uniform shell. The thickness of the Pt shell could be controlled from one to six atomic layers by varying the amount of Pt precursor added into the system. Compared to a commercial Pt/C catalyst, the Pd@PtnL (n = 1–6) core–shell nanocubes showed enhancements in specific activity and durability toward the oxygen reduction reaction (ORR). Density functional theory (DFT) calculations on model (100) surfaces suggest that the enhancement in specific activity can be attributed to the weakening of OH binding through ligand and strain effects, which, in turn, increases the rate of OH hydrogenation. A volcano-type relationship between the ORR specific activity and the number of Pt atomic layers was derived, in good agreement with the experimental results. Both theoretical and experimental studies indicate that the ORR specific activity was maximized for the catalysts based on Pd@Pt2–3L nanocubes. Because of the reduction in Pt content used and the enhancement in specific activity, the Pd@Pt1L nanocubes showed a Pt mass activity with almost three-fold enhancement relative to the Pt/C catalyst.

  16. Atomic Layer-by-Layer Deposition of Pt on Pd Nanocubes for Catalysts with Enhanced Activity and Durability toward Oxygen Reduction

    SciTech Connect

    Xie, Shuifen; Choi, Sang; Lu, Ning; Roling, Luke T.; Herron, Jeffrey A.; Zhang, Lei; Park, Jinho; Wang, Jinguo; Kim, Moon J.; Xie, Zhaoxiong; Mavrikakis, Manos; Xia, Younan

    2014-06-11

    An effective strategy for reducing the Pt content while retaining the activity of a Pt-based catalyst is to deposit the Pt atoms as ultrathin skins of only a few atomic layers thick on nanoscale substrates made of another metal. During deposition, however, the Pt atoms often take an island growth mode because of a strong bonding between Pt atoms. Here we report a versatile route to the conformal deposition of Pt as uniform, ultrathin shells on Pd nanocubes in a solution phase. The introduction of the Pt precursor at a relatively slow rate and high temperature allowed the deposited Pt atoms to spread across the entire surface of a Pd nanocube to generate a uniform shell. The thickness of the Pt shell could be controlled from one to six atomic layers by varying the amount of Pt precursor added into the system. Compared to a commercial Pt/C catalyst, the Pd@PnL (n = 1-6) core-shell nanocubes showed enhancements in specific activity and durability toward the oxygen reduction reaction (ORR). Density functional theory (DFT) calculations on model (100) surfaces suggest that the enhancement in specific activity can be attributed to the weakening of OH binding through ligand and strain effects, which, in turn, increases the rate of OH hydrogenation. A volcano-type relationship between the ORR specific activity and the number of Pt atomic layers was derived, in good agreement with the experimental results. Both theoretical and experimental studies indicate that the ORR specific activity was maximized for the catalysts based on Pd@Pt2-3L nanocubes. Because of the reduction in Pt content used and the enhancement in specific activity, the Pd@Pt1L nanocubes showed a Pt mass activity with almost three-fold enhancement relative to the Pt/C catalyst.

  17. Atomic Layer-by-Layer Deposition of Pt on Pd Nanocubes for Catalysts with Enhanced Activity and Durability toward Oxygen Reduction

    DOE PAGES

    Xie, Shuifen; Choi, Sang -Il; Lu, Ning; ...

    2014-05-05

    Here, an effective strategy for reducing the Pt content while retaining the activity of a Pt-based catalyst is to deposit the Pt atoms as ultrathin skins of only a few atomic layers thick on nanoscale substrates made of another metal. During deposition, however, the Pt atoms often take an island growth mode because of a strong bonding between Pt atoms. Here we report a versatile route to the conformal deposition of Pt as uniform, ultrathin shells on Pd nanocubes in a solution phase. The introduction of the Pt precursor at a relatively slow rate and high temperature allowed the depositedmore » Pt atoms to spread across the entire surface of a Pd nanocube to generate a uniform shell. The thickness of the Pt shell could be controlled from one to six atomic layers by varying the amount of Pt precursor added into the system. Compared to a commercial Pt/C catalyst, the Pd@PtnL (n = 1–6) core–shell nanocubes showed enhancements in specific activity and durability toward the oxygen reduction reaction (ORR). Density functional theory (DFT) calculations on model (100) surfaces suggest that the enhancement in specific activity can be attributed to the weakening of OH binding through ligand and strain effects, which, in turn, increases the rate of OH hydrogenation. A volcano-type relationship between the ORR specific activity and the number of Pt atomic layers was derived, in good agreement with the experimental results. Both theoretical and experimental studies indicate that the ORR specific activity was maximized for the catalysts based on Pd@Pt2–3L nanocubes. Because of the reduction in Pt content used and the enhancement in specific activity, the Pd@Pt1L nanocubes showed a Pt mass activity with almost three-fold enhancement relative to the Pt/C catalyst.« less

  18. Enhanced methane combustion over Co3O4 catalysts prepared by a facile precipitation method: Effect of aging time

    NASA Astrophysics Data System (ADS)

    Pu, Zhiying; Zhou, Huan; Zheng, Yifan; Huang, Wanzhen; Li, Xiaonian

    2017-07-01

    A series of Co3O4 catalysts were prepared by a facile precipitation method just changing the aging time and tested for methane combustion. It was found that the activity for the reaction increased firstly and then decreased with increasing aging time in the form of a volcano curve. The Co3O4 aged for 8 h (Co3O4-8) exhibited the best catalytic performance with the specific reaction rate (Rs) of 25.91 nmol s-1 m-2 at 340 °C, which was 29.5 times than Co3O4-96 sample, although the Co3O4-8 catalyst showed the minimum BET surface area and the largest particle size. The XPS and Raman results indicated that the Co3O4-8 catalyst possessed the highest ratio of ATetrahedral/AOctahedral at the surface of the catalyst. H2-TPR and in situ XRD results also confirmed the Co3O4-8 catalyst behaved with excellent high-temperature reduction ability. In combination with the activity performance, the Co3O4-8 catalyst had the best performance of methane combustion due to abundant active tetrahedral Co2+ cationic species. The long-term stability tests demonstrated that the step of aging in the process of preparation can improve water tolerance of Co3O4 catalyst for methane combustion.

  19. Oxygen-reducing catalyst layer

    DOEpatents

    O'Brien, Dennis P [Maplewood, MN; Schmoeckel, Alison K [Stillwater, MN; Vernstrom, George D [Cottage Grove, MN; Atanasoski, Radoslav [Edina, MN; Wood, Thomas E [Stillwater, MN; Yang, Ruizhi [Halifax, CA; Easton, E Bradley [Halifax, CA; Dahn, Jeffrey R [Hubley, CA; O'Neill, David G [Lake Elmo, MN

    2011-03-22

    An oxygen-reducing catalyst layer, and a method of making the oxygen-reducing catalyst layer, where the oxygen-reducing catalyst layer includes a catalytic material film disposed on a substrate with the use of physical vapor deposition and thermal treatment. The catalytic material film includes a transition metal that is substantially free of platinum. At least one of the physical vapor deposition and the thermal treatment is performed in a processing environment comprising a nitrogen-containing gas.

  20. Enhanced effect of water vapor on complete oxidation of formaldehyde in air with ozone over MnOx catalysts at room temperature.

    PubMed

    Zhao, De-Zhi; Shi, Chuan; Li, Xiao-Song; Zhu, Ai-Min; Jang, Ben W-L

    2012-11-15

    At room temperature, the enhanced effect of water vapor on ozone catalytic oxidation (OZCO) of formaldehyde to CO2 over MnOx catalysts and the reaction stability was reported. In a dry air stream, only below 20% of formaldehyde could be oxidized into CO2 by O3. In humid air streams (RH≥55%), ∼100% of formaldehyde were oxidized into CO2 by O3 and the reaction stability was significantly enhanced. Meanwhile, in situ Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectra of OZCO of HCHO demonstrate that the amount of both monodentate and bidentate carbonate species on MnOx, in the dry stream, increased gradually with time on stream (TOS). However, in the humid stream, almost no accumulation of carbonate species on the catalysts was observed. To clarify the enhanced mechanism, formaldehyde surface reactions and CO2 adsorption/desorption on the fresh, O3 and O3+H2O treated MnOx catalysts were examined comparatively. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Enhanced development of a catalyst chamber for the decomposition of up to 1.0 kg/s hydrogen peroxide

    NASA Astrophysics Data System (ADS)

    Božić, Ognjan; Porrmann, Dennis; Lancelle, Daniel; May, Stefan

    2016-06-01

    A new innovative hybrid rocket engine concept is developed within the AHRES program of the German Aerospace Center (DLR). This rocket engine based on hydroxyl-terminated polybutadiene (HTPB) with metallic additives as solid fuel and high test peroxide (HTP) as liquid oxidizer. Instead of a conventional ignition system, a catalyst chamber with a silver mesh catalyst is designed to decompose the HTP. The newly modified catalyst chamber is able to decompose up to 1.0 kg/s of 87.5 wt% HTP. Used as a monopropellant thruster, this equals an average thrust of 1600 N. The catalyst chamber is designed using the self-developed software tool SHAKIRA. The applied kinetic law, which determines catalytic decomposition of HTP within the catalyst chamber, is given and commented. Several calculations are carried out to determine the appropriate geometry for complete decomposition with a minimum of catalyst material. A number of tests under steady state conditions are carried out, using 87.5 wt% HTP with different flow rates and a constant amount of catalyst material. To verify the decomposition, the temperature is measured and compared with the theoretical prediction. The experimental results show good agreement with the results generated by the design tool. The developed catalyst chamber provides a simple, reliable ignition system for hybrid rocket propulsion systems based on hydrogen peroxide as oxidizer. This system is capable for multiple reignition. The developed hardware and software can be used to design full scale monopropellant thrusters based on HTP and catalyst chambers for hybrid rocket engines.

  2. Enhanced catalytic activity over MIL-100(Fe) loaded ceria catalysts for the selective catalytic reduction of NOx with NH₃ at low temperature.

    PubMed

    Wang, Peng; Sun, Hong; Quan, Xie; Chen, Shuo

    2016-01-15

    The development of catalysts for selective catalytic reduction (SCR) reactions that are highly active at low temperatures and show good resistance to SO2 and H2O is still a challenge. In this study, we have designed and developed a high-performance SCR catalyst based on nano-sized ceria encapsulated inside the pores of MIL-100(Fe) that combines excellent catalytic power with a metal organic framework architecture synthesized by the impregnation method (IM). Transmission electron microscopy (TEM) revealed the encapsulation of ceria in the cavities of MIL-100(Fe). The prepared IM-CeO2/MIL-100(Fe) catalyst shows improved catalytic activity both at low temperatures and throughout a wide temperature window. The temperature window for 90% NOx conversion ranges from 196 to 300°C. X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) analysis indicated that the nano-sized ceria encapsulated inside MIL-100(Fe) promotes the production of chemisorbed oxygen on the catalyst surface, which greatly enhances the formation of the NO2 species responsible for fast SCR reactions.

  3. Pt-free carbon-based fuel cell catalyst prepared from spherical polyimide for enhanced oxygen diffusion.

    PubMed

    Nabae, Yuta; Nagata, Shinsuke; Hayakawa, Teruaki; Niwa, Hideharu; Harada, Yoshihisa; Oshima, Masaharu; Isoda, Ayano; Matsunaga, Atsushi; Tanaka, Kazuhisa; Aoki, Tsutomu

    2016-03-18

    The development of a non-precious metal (NPM) fuel cell catalyst is extremely important to achieve globalization of polymer electrolyte fuel cells due to the cost and scarcity of platinum. Here, we report on a NPM cathode catalyst prepared by the pyrolysis of spherical polyimide nanoparticles that contain small amounts of Fe additive. 60 nm diameter Fe-containing polyimide nanoparticles were successfully synthesized by the precipitation polymerization of pyromellitic acid dianhydride and 1,3,5-tris(4-aminophenyl)benzene with Fe(acac)3 (acac = acetylacetonate) as an additive. The particles were subsequently carbonized by multistep pyrolysis to obtain the NPM catalyst while retaining the small particle size. The catalyst has good performance and promising durability for fuel cell applications. The fuel cell performance under a 0.2 MPa air atmosphere at 80 °C of 1.0 A cm(-2) at 0.46 V is especially remarkable and better than that previously reported.

  4. Enhanced Hydrodeoxygenation of m -Cresol over Bimetallic Pt–Mo Catalysts through an Oxophilic Metal-Induced Tautomerization Pathway

    DOE PAGES

    Robinson, Allison; Ferguson, Glen Allen; Gallagher, James R.; ...

    2016-05-26

    Supported bimetallic catalysts consisting of a noble metal (e.g., Pt) and an oxophilic metal (e.g., Mo) have received considerable attention for the hydrodeoxygenation of oxygenated aromatic compounds produced from biomass fast pyrolysis. Here, we report that PtMo can catalyze m-cresol deoxygenation via a pathway involving an initial tautomerization step. In contrast, the dominant mechanism on monometallic Pt/Al2O3 was found to be sequential Pt-catalyzed ring hydrogenation followed by dehydration on the support. Bimetallic Pt10Mo1 and Pt1Mo1 catalysts were found to produce the completely hydrogenated and deoxygenated product, methylcyclohexane (MCH), with much higher yields than monometallic Pt catalysts with comparable metal loadingsmore » and surface areas. Over an inert carbon support, MCH formation was found to be slow over monometallic Pt catalysts, while deoxygenation was significant for PtMo catalysts even in the absence of an acidic support material. Experimental studies of m-cresol deoxygenation together with density functional theory calculations indicated that Mo sites on the PtMo bimetallic surface dramatically lower the barrier for m-cresol tautomerization and subsequent deoxygenation. The accessibility of this pathway arises from the increased interaction between the oxygen of m-cresol and the Mo sites in the Pt surface. This interaction significantly alters the configuration of the precursor and transition states for tautomerization. Lastly, a suite of catalyst characterization techniques including X-ray absorption spectroscopy (XAS) and temperature-programmed reduction (TPR) indicate that Mo was present in a reduced state on the bimetallic surface under conditions relevant for reaction. Overall, these results suggest that the use of bifunctional metal catalysts can result in new reaction pathways that are unfavorable on monometallic noble metal catalysts.« less

  5. Lipid cross-linking of nanolipoprotein particles substantially enhances serum stability and cellular uptake [Lipid crosslinking enhances the stability of nanolipoprotein particles in serum by multiple orders of magnitude

    DOE PAGES

    Gilmore, Sean F.; Blanchette, Craig D.; Scharadin, Tiffany M.; ...

    2016-07-13

    Nanolipoprotein particles (NLPs) consist of a discoidal phospholipid lipid bilayer confined by an apolipoprotein belt. NLPs are a promising platform for a variety of biomedical applications due to their biocompatibility, size, definable composition, and amphipathic characteristics. However, poor serum stability hampers the use of NLPs for in vivo applications such as drug formulation. In this study, NLP stability was enhanced upon the incorporation and subsequent UV-mediated intermolecular cross-linking of photoactive DiynePC phospholipids in the lipid bilayer, forming cross-linked nanoparticles (X-NLPs). Both the concentration of DiynePC in the bilayer and UV exposure time significantly affected the resulting X-NLP stability in 100%more » serum, as assessed by size exclusion chromatography (SEC) of fluorescently labeled particles. Cross-linking did not significantly impact the size of X-NLPs as determined by dynamic light scattering and SEC. X-NLPs had essentially no degradation over 48 h in 100% serum, which is a drastic improvement compared to non-cross-linked NLPs (50% degradation by ~10 min). X-NLPs had greater uptake into the human ATCC 5637 bladder cancer cell line compared to non-cross-linked particles, indicating their potential utility for targeted drug delivery. X-NLPs also exhibited enhanced stability following intravenous administration in mice. Lastly, these results collectively support the potential utility of X-NLPs for a variety of in vivo applications.« less

  6. Lipid cross-linking of nanolipoprotein particles substantially enhances serum stability and cellular uptake [Lipid crosslinking enhances the stability of nanolipoprotein particles in serum by multiple orders of magnitude

    SciTech Connect

    Gilmore, Sean F.; Blanchette, Craig D.; Scharadin, Tiffany M.; Hura, Greg L.; Rasley, Amy; Corzett, Michele; Pan, Chong-xian; Fischer, Nicholas O.; Henderson, Paul T.

    2016-07-13

    Nanolipoprotein particles (NLPs) consist of a discoidal phospholipid lipid bilayer confined by an apolipoprotein belt. NLPs are a promising platform for a variety of biomedical applications due to their biocompatibility, size, definable composition, and amphipathic characteristics. However, poor serum stability hampers the use of NLPs for in vivo applications such as drug formulation. In this study, NLP stability was enhanced upon the incorporation and subsequent UV-mediated intermolecular cross-linking of photoactive DiynePC phospholipids in the lipid bilayer, forming cross-linked nanoparticles (X-NLPs). Both the concentration of DiynePC in the bilayer and UV exposure time significantly affected the resulting X-NLP stability in 100% serum, as assessed by size exclusion chromatography (SEC) of fluorescently labeled particles. Cross-linking did not significantly impact the size of X-NLPs as determined by dynamic light scattering and SEC. X-NLPs had essentially no degradation over 48 h in 100% serum, which is a drastic improvement compared to non-cross-linked NLPs (50% degradation by ~10 min). X-NLPs had greater uptake into the human ATCC 5637 bladder cancer cell line compared to non-cross-linked particles, indicating their potential utility for targeted drug delivery. X-NLPs also exhibited enhanced stability following intravenous administration in mice. Lastly, these results collectively support the potential utility of X-NLPs for a variety of in vivo applications.

  7. Lipid cross-linking of nanolipoprotein particles substantially enhances serum stability and cellular uptake [Lipid crosslinking enhances the stability of nanolipoprotein particles in serum by multiple orders of magnitude

    SciTech Connect

    Gilmore, Sean F.; Blanchette, Craig D.; Scharadin, Tiffany M.; Hura, Greg L.; Rasley, Amy; Corzett, Michele; Pan, Chong-xian; Fischer, Nicholas O.; Henderson, Paul T.

    2016-07-13

    Nanolipoprotein particles (NLPs) consist of a discoidal phospholipid lipid bilayer confined by an apolipoprotein belt. NLPs are a promising platform for a variety of biomedical applications due to their biocompatibility, size, definable composition, and amphipathic characteristics. However, poor serum stability hampers the use of NLPs for in vivo applications such as drug formulation. In this study, NLP stability was enhanced upon the incorporation and subsequent UV-mediated intermolecular cross-linking of photoactive DiynePC phospholipids in the lipid bilayer, forming cross-linked nanoparticles (X-NLPs). Both the concentration of DiynePC in the bilayer and UV exposure time significantly affected the resulting X-NLP stability in 100% serum, as assessed by size exclusion chromatography (SEC) of fluorescently labeled particles. Cross-linking did not significantly impact the size of X-NLPs as determined by dynamic light scattering and SEC. X-NLPs had essentially no degradation over 48 h in 100% serum, which is a drastic improvement compared to non-cross-linked NLPs (50% degradation by ~10 min). X-NLPs had greater uptake into the human ATCC 5637 bladder cancer cell line compared to non-cross-linked particles, indicating their potential utility for targeted drug delivery. X-NLPs also exhibited enhanced stability following intravenous administration in mice. Lastly, these results collectively support the potential utility of X-NLPs for a variety of in vivo applications.

  8. Epoxidation catalyst and process

    DOEpatents

    Linic, Suljo; Christopher, Phillip

    2010-10-26

    Disclosed herein is a catalytic method of converting alkenes to epoxides. This method generally includes reacting alkenes with oxygen in the presence of a specific silver catalyst under conditions suitable to produce a yield of the epoxides. The specific silver catalyst is a silver nanocrystal having a plurality of surface planes, a substantial portion of which is defined by Miller indices of (100). The reaction is performed by charging a suitable reactor with this silver catalyst and then feeding the reactants to the reactor under conditions to carry out the reaction. The reaction may be performed in batch, or as a continuous process that employs a recycle of any unreacted alkenes. The specific silver catalyst has unexpectedly high selectivity for epoxide products. Consequently, this general method (and its various embodiments) will result in extraordinarily high epoxide yields heretofore unattainable.

  9. Ternary Pt9RhFex Nanoscale Alloys as Highly Efficient Catalysts with Enhanced Activity and Excellent CO-Poisoning Tolerance for Ethanol Oxidation.

    PubMed

    Wang, Peng; Yin, Shibin; Wen, Ying; Tian, Zhiqun; Wang, Ningzhang; Key, Julian; Wang, Shuangbao; Shen, Pei Kang

    2017-03-13

    To address the problems of high cost and poor stability of anode catalysts in direct ethanol fuel cells (DEFCs), ternary nanoparticles Pt9RhFex (x = 1, 3, 5, 7, and 9) supported on carbon powders (XC-72R) have been synthesized via a facile method involving reduction by sodium borohydride followed by thermal annealing in N2 at ambient pressure. The catalysts are physically characterized by X-ray diffraction, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy, and their catalytic performance for the ethanol oxidation reaction (EOR) is evaluated by cyclic and linear scan voltammetry, CO-stripping voltammograms, and chronopotentiometry. All the Pt9RhFex/C catalysts of different atomic ratios produce high EOR catalytic activity. The catalyst of atomic ratio composition 9:1:3 (Pt/Rh/Fe) has the highest activity and excellent CO-poisoning tolerance. Moreover, the enhanced EOR catalytic activity on Pt9RhFe3/C when compared to Pt9Rh/C, Pt3Fe/C, and Pt/C clearly demonstrates the presence of Fe improves catalytic performance. Notably, the onset potential for CO oxidation on Pt9RhFe3/C (0.271 V) is ∼55, 75, and 191 mV more negative than on Pt9Rh/C (0.326 V), Pt3Fe/C (0.346 V), and Pt/C (0.462 V), respectively, which implies the presence of Fe atoms dramatically improves CO-poisoning tolerance. Meanwhile, compared to the commercial PtRu/C catalyst, the peak potential on Pt9RhFe3/C for CO oxidation was just slightly changed after several thousand cycles, which shows high stability against the potential cycling. The possible mechanism by which Fe and Rh atoms facilitate the observed enhanced performance is also considered herein, and we conclude Pt9RhFe3/C offers a promising anode catalyst for direct ethanol fuel cells.

  10. Enhancing low-temperature activity and durability of Pd-based diesel oxidation catalysts using ZrO2 supports

    DOE PAGES

    Kim, Mi -Young; Kyriakidou, Eleni A.; Choi, Jae -Soon; ...

    2016-01-18

    In this study, we investigated the impact of ZrO2 on the performance of palladium-based oxidation catalysts with respect to low-temperature activity, hydrothermal stability, and sulfur tolerance. Pd supported on ZrO2 and SiO2 were synthesized for a comparative study. Additionally, in an attempt to maximize the ZrO2 surface area and improve sulfur tolerance, a Pd support with ZrO2-dispersed onto SiO2 was studied. The physicochemical properties of the catalysts were examined using ICP, N2 sorption, XRD, SEM, TEM, and NH3-, CO2-, and NOx-TPD. The activity of the Pd catalysts were measured from 60 to 600 °C in a flow of 4000 ppmmore » CO, 500 ppm NO, 1000 ppm C3H6, 4% O2, 5% H2O, and Ar balance. The Pd catalysts were evaluated in fresh, sulfated, and hydrothermally aged states. Overall, the ZrO2-containing catalysts showed considerably higher CO and C3H6 oxidation activity than Pd/SiO2 under the reaction conditions studied.« less

  11. Effect of nitrogen post-doping on a commercial platinum-ruthenium/carbon anode catalyst

    NASA Astrophysics Data System (ADS)

    Corpuz, April R.; Wood, Kevin N.; Pylypenko, Svitlana; Dameron, Arrelaine A.; Joghee, Prabhuram; Olson, Tim S.; Bender, Guido; Dinh, Huyen N.; Gennett, Thomas; Richards, Ryan M.; O'Hayre, Ryan

    2014-02-01

    This work investigates the effects of after-the-fact chemical modification of a state-of-the-art commercial carbon-supported PtRu catalyst for direct methanol fuel cells (DMFCs). A commercial PtRu/C (JM HiSPEC-10000) catalyst is post-doped with nitrogen by ion-implantation, where "post-doped" denotes nitrogen doping after metal is carbon-supported. Composition and performance of the PtRu/C catalyst post-modified with nitrogen at several dosages are evaluated using X-ray photoelectron spectroscopy (XPS), rotating disk electrode (RDE), and membrane electrode assemblies (MEAs) for DMFC. Overall, implantation at high dosage results in 16% higher electrochemical surface area and enhances performance, specifically in the mass transfer region. Rotating disk electrode (RDE) results show that after 5000 cycles of accelerated durability testing to high potential, the modified catalyst retains 34% more electrochemical surface area (ECSA) than the unmodified catalyst. The benefits of nitrogen post-doping are further substantiated by DMFC durability studies (carried out for 425 h), where the MEA with the modified catalyst exhibits higher surface area and performance stability in comparison to the MEA with unmodified catalyst. These results demonstrate that post-doping of nitrogen in a commercial PtRu/C catalyst is an effective approach, capable of improving the performance of available best-in-class commercial catalysts.

  12. Production of substantially pure fructose

    SciTech Connect

    Hatcher, H.J.; Gallian, J.J.; Leeper, S.A.

    1990-05-22

    This patent describes a process for the production of a substantially pure product containing greater than 60% fructose. It comprises: combining a sucrose-containing substrate with effective amounts of a levansucrase enzyme preparation to form levan and glucose; purifying the levan by at least one of the following purification methods: ultrafiltration, diafiltration, hyperfiltration, reverse osmosis, liquid--liquid partition, solvent extraction, chromatography, and precipitation; hydrolyzing the levan to form fructose substantially free of glucose and sucrose; and recovering the fructose by at least one of the following recovery methods: hyperfiltration, reverse osmosis, evaporation, drying, crystallization, and chromatography.

  13. Application of meta- and para- phenylenediamine as enhanced oxime ligation catalysts for protein labeling, PEGylation, immobilization and release

    PubMed Central

    Mahmoodi, Mohammad M.; Rashidian, Mohammad; Zhang, Yi; Distefano, Mark D.

    2015-01-01

    Meta- and para- phenylenediamines have recently been shown to catalyze oxime and hydrazone ligation reactions at rates much faster than aniline, a commonly used catalyst. Here, it is demonstrated how these new catalysts can be used in a generally applicable procedure for fluorescent labeling, PEGylation, immobilization and release of aldehyde and ketone functionalized proteins. The chemical orthogonality of phenylenediamine-catalyzed oxime ligation versus copper catalyzed click reaction has also been harnessed for simultaneous dual labeling of bifunctional proteins containing both aldehyde and alkyne groups in high yield. PMID:25640893

  14. Application of meta- and para-Phenylenediamine as Enhanced Oxime Ligation Catalysts for Protein Labeling, PEGylation, Immobilization, and Release.

    PubMed

    Mahmoodi, Mohammad M; Rashidian, Mohammad; Zhang, Yi; Distefano, Mark D

    2015-02-02

    Meta- and para-phenylenediamines have recently been shown to catalyze oxime and hydrazone ligation reactions at rates much faster than aniline, a commonly used catalyst. Here, we demonstrate how these new catalysts can be used in a generally applicable procedure for fluorescent labeling, PEGylation, immobilization, and release of aldehyde- and ketone- functionalized proteins. The chemical orthogonality of phenylenediamine-catalyzed oxime ligation versus copper-catalyzed click reaction has also been harnessed for simultaneous dual labeling of bifunctional proteins containing both aldehyde and alkyne groups in high yield.

  15. When Magnetic Catalyst Meets Magnetic Reactor: Etherification of FCC Light Gasoline as an Example

    NASA Astrophysics Data System (ADS)

    Cheng, Meng; Xie, Wenhua; Zong, Baoning; Sun, Bo; Qiao, Minghua

    2013-06-01

    The application of elaborately designed magnetic catalysts has long been limited to ease their separation from the products only. In this paper, we for the first time employed a magnetic sulphonated poly(styrene-divinylbenzene) resin catalyst on a magnetically stabilized-bed (MSB) reactor to enhance the etherification of fluidized catalytic cracking (FCC) light gasoline, one of the most important reactions in petroleum refining industry. We demonstrated that the catalytic performance of the magnetic acid resin catalyst on the magnetic reactor is substantially enhanced as compared to its performance on a conventional fixed-bed reactor under otherwise identical operation conditions. The magnetic catalyst has the potential to be loaded and unloaded continuously on the magnetic reactor, which will greatly simplify the current complex industrial etherification processes.

  16. When Magnetic Catalyst Meets Magnetic Reactor: Etherification of FCC Light Gasoline as an Example

    PubMed Central

    Cheng, Meng; Xie, Wenhua; Zong, Baoning; Sun, Bo; Qiao, Minghua

    2013-01-01

    The application of elaborately designed magnetic catalysts has long been limited to ease their separation from the products only. In this paper, we for the first time employed a magnetic sulphonated poly(styrene-divinylbenzene) resin catalyst on a magnetically stabilized-bed (MSB) reactor to enhance the etherification of fluidized catalytic cracking (FCC) light gasoline, one of the most important reactions in petroleum refining industry. We demonstrated that the catalytic performance of the magnetic acid resin catalyst on the magnetic reactor is substantially enhanced as compared to its performance on a conventional fixed-bed reactor under otherwise identical operation conditions. The magnetic catalyst has the potential to be loaded and unloaded continuously on the magnetic reactor, which will greatly simplify the current complex industrial etherification processes. PMID:23756855

  17. When magnetic catalyst meets magnetic reactor: etherification of FCC light gasoline as an example.

    PubMed

    Cheng, Meng; Xie, Wenhua; Zong, Baoning; Sun, Bo; Qiao, Minghua

    2013-01-01

    The application of elaborately designed magnetic catalysts has long been limited to ease their separation from the products only. In this paper, we for the first time employed a magnetic sulphonated poly(styrene-divinylbenzene) resin catalyst on a magnetically stabilized-bed (MSB) reactor to enhance the etherification of fluidized catalytic cracking (FCC) light gasoline, one of the most important reactions in petroleum refining industry. We demonstrated that the catalytic performance of the magnetic acid resin catalyst on the magnetic reactor is substantially enhanced as compared to its performance on a conventional fixed-bed reactor under otherwise identical operation conditions. The magnetic catalyst has the potential to be loaded and unloaded continuously on the magnetic reactor, which will greatly simplify the current complex industrial etherification processes.

  18. Production of substantially pure fructose

    DOEpatents

    Hatcher, Herbert J.; Gallian, John J.; Leeper, Stephen A.

    1990-01-01

    A process is disclosed for the production of substantially pure fructose from sucrose-containing substrates. The process comprises converting the sucrose to levan and glucose, purifying the levan by membrane technology, hydrolyzing the levan to form fructose monomers, and recovering the fructose.

  19. Enhanced photo-Fenton degradation of rhodamine B using graphene oxide-amorphous FePO₄ as effective and stable heterogeneous catalyst.

    PubMed

    Guo, Sheng; Zhang, Gaoke; Yu, Jimmy C

    2015-06-15

    A series of graphene oxide (GO)-FePO4 composites with different GO weight ratios (2.5%, 5%, 10%, w/w) were prepared using a simple precipitation process and were firstly used as heterogeneous photo-Fenton catalysts. FESEM images prove the loose structure of the 5GO-FePO4 composite. UV-vis analysis demonstrates that the introduction of GO could enhance solar energy utilization of the composites. Under visible light irradiation, the degradation rate of rhodamine B (RhB) by the 5GO-FePO4 composite was 2.87 times more than that by the pure FePO4 in the presence of hydrogen peroxide. The composite was highly effective for the degradation of RhB in a wide pH range of 2.18-10.40 with negligible iron leaching. Moreover, the composite still showed high catalytic activity after six cycles, which makes it a promising heterogeneous catalyst for wastewater treatment. The introduction of GO promotes the photo-Fenton reaction of GO-FePO4 via three roles: offering more active sites, increasing adsorption capacity and accelerating the Fe(3+)/Fe(2+) cycle by improving the utilization of solar energy. Our work may provide new insights for the development of new effective heterogeneous photo-Fenton catalyst. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Electrochemical enhanced heterogeneous activation of peroxydisulfate by Fe-Co/SBA-15 catalyst for the degradation of Orange II in water.

    PubMed

    Cai, Chun; Zhang, Hui; Zhong, Xin; Hou, Liwei

    2014-12-01

    Mesoporous silica SBA-15 supported iron and cobalt catalysts (Fe-Co/SBA-15) were prepared and used in the electrochemical (EC) enhanced heterogeneous activation of peroxydisulfate (PDS, S2O8(2-)) process for the removal of Orange II. The effects of some important reaction parameters such as initial pH, current density, PDS concentration and dosage of Fe-Co/SBA-15 catalysts were investigated. The results showed that the decolorization efficiency was not significantly affected by the initial pH value, and it did increase with the higher PDS concentration, current density and Fe-Co/SBA-15 dosage. Both the sulfate radical (SO4(·-)) and the hydroxyl radical (OH) are considered as the primary reactive oxidants for the Orange II decolorization. The Fe-Co/SBA-15 catalyst maintained its high activity during repeated batch experiments. The intermediate products were identified by GC-MS analysis and a plausible degradation pathway is proposed accordingly. The removal efficiencies of chemical oxygen demand (COD) and total organic carbon (TOC) were 52.1% and 31.9%, respectively after 60 min of reaction time but reached 82.9% and 51.5%, respectively when the reaction time was extended to 24 h. Toxicity tests with activated sludge indicated that the toxicity of the solution increased during the first 30 min and then decreased as the oxidation proceeded.

  1. Bismuth as a modifier of Au Pd catalyst: Enhancing selectivity in alcohol oxidation by suppressing parallel reaction

    SciTech Connect

    Villa, Alberto; Wang, Di; Veith, Gabriel M; Prati, Laura

    2012-01-01

    Bi has been widely employed as a modifier for Pd and Pt based catalyst mainly in order to improve selectivity. We found that when Bi was added to the bimetallic system AuPd, the effect on activity in alcohol oxidation mainly depends on the amount of Bi regardless its position, being negligible when Bi was 0.1 wt% and detectably negative when the amount was increased to 3 wt%. However, the selectivity of the reactions notably varied only when Bi was deposited on the surface of metal nanoparticles suppressing parallel reaction in both benzyl alcohol and glycerol oxidation. After a careful characterization of all the catalysts and additional catalytic tests, we concluded that the Bi influence on the activity of the catalysts could be ascribed to electronic effect whereas the one on selectivity mainly to a geometric modification. Moreover, the Bi-modified AuPd/AC catalyst showed possible application in the production of tartronic acid, a useful intermediate, from glycerol.

  2. Pt-free carbon-based fuel cell catalyst prepared from spherical polyimide for enhanced oxygen diffusion

    PubMed Central

    Nabae, Yuta; Nagata, Shinsuke; Hayakawa, Teruaki; Niwa, Hideharu; Harada, Yoshihisa; Oshima, Masaharu; Isoda, Ayano; Matsunaga, Atsushi; Tanaka, Kazuhisa; Aoki, Tsutomu

    2016-01-01

    The development of a non-precious metal (NPM) fuel cell catalyst is extremely important to achieve globalization of polymer electrolyte fuel cells due to the cost and scarcity of platinum. Here, we report on a NPM cathode catalyst prepared by the pyrolysis of spherical polyimide nanoparticles that contain small amounts of Fe additive. 60 nm diameter Fe-containing polyimide nanoparticles were successfully synthesized by the precipitation polymerization of pyromellitic acid dianhydride and 1,3,5-tris(4-aminophenyl)benzene with Fe(acac)3 (acac = acetylacetonate) as an additive. The particles were subsequently carbonized by multistep pyrolysis to obtain the NPM catalyst while retaining the small particle size. The catalyst has good performance and promising durability for fuel cell applications. The fuel cell performance under a 0.2 MPa air atmosphere at 80 °C of 1.0 A cm−2 at 0.46 V is especially remarkable and better than that previously reported. PMID:26987682

  3. Pt-free carbon-based fuel cell catalyst prepared from spherical polyimide for enhanced oxygen diffusion

    NASA Astrophysics Data System (ADS)

    Nabae, Yuta; Nagata, Shinsuke; Hayakawa, Teruaki; Niwa, Hideharu; Harada, Yoshihisa; Oshima, Masaharu; Isoda, Ayano; Matsunaga, Atsushi; Tanaka, Kazuhisa; Aoki, Tsutomu

    2016-03-01

    The development of a non-precious metal (NPM) fuel cell catalyst is extremely important to achieve globalization of polymer electrolyte fuel cells due to the cost and scarcity of platinum. Here, we report on a NPM cathode catalyst prepared by the pyrolysis of spherical polyimide nanoparticles that contain small amounts of Fe additive. 60 nm diameter Fe-containing polyimide nanoparticles were successfully synthesized by the precipitation polymerization of pyromellitic acid dianhydride and 1,3,5-tris(4-aminophenyl)benzene with Fe(acac)3 (acac = acetylacetonate) as an additive. The particles were subsequently carbonized by multistep pyrolysis to obtain the NPM catalyst while retaining the small particle size. The catalyst has good performance and promising durability for fuel cell applications. The fuel cell performance under a 0.2 MPa air atmosphere at 80 °C of 1.0 A cm‑2 at 0.46 V is especially remarkable and better than that previously reported.

  4. Bifunctional enhancement of oxygen reduction reaction activity on Ag catalysts due to water activation on LaMnO3 supports in alkaline media

    PubMed Central

    Park, Shin-Ae; Lee, Eun-Kyung; Song, Hannah; Kim, Yong-Tae

    2015-01-01

    Ag is considered to be one of the best candidates for oxygen reduction reaction electrocatalysts in alkaline media for application in various electrochemical energy devices. In this study, we demonstrate that water activation is a key factor in enhancing the ORR activity in alkaline media, unlike in acid environments. Ag supported on LaMnO3 having a high oxophilicity showed a markedly higher ORR activity than that on carbon with inert surfaces. Through various electrochemical tests, it was revealed that the origin of the enhanced ORR activity of Ag/LaMnO3 is the bifunctional effect mainly due to the water activation at the interface between Ag and LaMnO3. Furthermore, the ligand effect due to the charge transfer from Mn to Ag leads to the enhancement of both oxygen activation on Ag and water activation on Mn sites, and hence, an improvement in the ORR activity of Ag/LaMnO3. On the other hand, the strain effect based on the fine structure variation in the lattice was negligible. We therefore suggest that the employment of a co-catalyst or support with highly oxophilic nature and the maximization of the interface between catalyst and support should be considered in the design of electrocatalysts for the ORR in alkaline media. PMID:26310526

  5. SR-135, a Peroxynitrite Decomposing Catalyst, Enhances β-cell Function and Survival in B6D2F1 Mice Fed a High Fat Diet

    PubMed Central

    Johns, Michael; Fyalka, Robert; Shea, Jennifer A.; Neumann, William L.; Rausaria, Smita; Msengi, Eliwaza Naomi; Imani-Nejad, Maryam; Zollars, Harry; McPherson, Timothy; Schober, Joseph; Wooten, Joshua; Kwon, Guim

    2015-01-01

    Peroxynitrite has been implicated in β-cell dysfunction and insulin resistance in obesity. Chemical catalysts that destroy peroxynitrite, therefore, may have therapeutic value for treating type 2 diabetes. To this end, we have recently demonstrated that Mn(III) bis(hydroxyphenyl)-dipyrromethene complexes, SR-135 and its analogues, can effectively catalyze the decomposition of peroxynitrite in vitro and in vivo through a 2-electron mechanism (Rausaria et al. 2011). To study the effects of SR-135 on glucose homeostasis in obesity, B6D2F1 mice were fed with a high fat-diet (HFD) for 12 weeks and treated with vehicle, SR-135 (5 mg/kg), or a control drug SRB for 2 weeks. SR-135 significantly reduced fasting blood glucose and insulin levels, and enhanced glucose tolerance as compared to HFD control, vehicle or SRB. SR-135 also enhanced glucose-stimulated insulin secretion based on ex vivo studies. Moreover, SR-135 increased insulin content, restored islet architecture, decreased islet size, and reduced tyrosine nitration and apoptosis. These results suggest that a peroxynitrite decomposing catalyst enhances β-cell function and survival under nutrient overload. PMID:25935364

  6. Investigation of Mixed Oxide Catalysts for NO Oxidation

    SciTech Connect

    Szanyi, Janos; Karim, Ayman M.; Pederson, Larry R.; Kwak, Ja Hun; Mei, Donghai; Tran, Diana N.; Herling, Darrell R.; Muntean, George G.; Peden, Charles HF; Howden, Ken; Qi, Gongshin; Li, Wei

    2014-12-09

    The oxidation of engine-generated NO to NO2 is an important step in the reduction of NOx in lean engine exhaust because NO2 is required for the performance of the LNT technology [2], and it enhances the activities of ammonia selective catalytic reduction (SCR) catalysts [1]. In particular, for SCR catalysts an NO:NO2 ratio of 1:1 is most effective for NOx reduction, whereas for LNT catalysts, NO must be oxidized to NO2 before adsorption on the storage components. However, NO2 typically constitutes less than 10% of NOx in lean exhaust, so catalytic oxidation of NO is essential. Platinum has been found to be especially active for NO oxidation, and is widely used in DOC and LNT catalysts. However, because of the high cost and poor thermal durability of Pt-based catalysts, there is substantial interest in the development of alternatives. The objective of this project, in collaboration with partner General Motors, is to develop mixed metal oxide catalysts for NO oxidation, enabling lower precious metal usage in emission control systems. [1] M. Koebel, G. Madia, and M. Elsener, Catalysis Today 73, 239 (2002). [2] C. H. Kim, G. S. Qi, K. Dahlberg, and W. Li, Science 327, 1624 (2010).

  7. Modeling Geometric Arrangements of TiO2-Based Catalyst Substrates and Isotropic Light Sources to Enhance the Efficiency of a Photocatalystic Oxidation (PCO) Reactor

    NASA Technical Reports Server (NTRS)

    Richards, Jeffrey T.; Levine, Lanfang H.; Husk, Geoffrey K.

    2011-01-01

    The closed confined environments of the ISS, as well as in future spacecraft for exploration beyond LEO, provide many challenges to crew health. One such challenge is the availability of a robust, energy efficient, and re-generable air revitalization system that controls trace volatile organic contaminants (VOCs) to levels below a specified spacecraft maximum allowable concentration (SMAC). Photocatalytic oxidation (PCO), which is capable of mineralizing VOCs at room temperature and of accommodating a high volumetric flow, is being evaluated as an alternative trace contaminant control technology. In an architecture of a combined air and water management system, placing a PCO unit before a condensing heat exchanger for humidity control will greatly reduce the organic load into the humidity condensate loop ofthe water processing assembly (WPA) thereby enhancing the life cycle economics ofthe WPA. This targeted application dictates a single pass efficiency of greater than 90% for polar VOCs. Although this target was met in laboratory bench-scaled reactors, no commercial or SBIR-developed prototype PCO units examined to date have achieved this goal. Furthermore, the formation of partial oxidation products (e.g., acetaldehyde) was not eliminated. It is known that single pass efficiency and partial oxidation are strongly dependent upon the contact time and catalyst illumination, hence the requirement for an efficient reactor design. The objective of this study is to maximize the apparent contact time and illuminated catalyst surface area at a given reactor volume and volumetric flow. In this study, a Ti02-based photocatalyst is assumed to be immobilized on porous substrate panels and illumination derived from linear isotropic light sources. Mathematical modeling using computational fluid dynamics (CFD) analyses were performed to investigate the effect of: 1) the geometry and configuration of catalyst-coated substrate panels, 2) porosity of the supporting substrate, and 3

  8. Nanostructured Ti(0.7)Mo(0.3)O2 support enhances electron transfer to Pt: high-performance catalyst for oxygen reduction reaction.

    PubMed

    Ho, Van Thi Thanh; Pan, Chun-Jern; Rick, John; Su, Wei-Nien; Hwang, Bing-Joe

    2011-08-03

    The slow rate of the oxygen reduction reaction (ORR) and the instability of Pt-based catalysts are two of the most important issues that must be solved in order to make proton exchange membrane fuel cells (PEMFCs) a reality. Additionally, the serious carbon corrosion on the cathode side is a critical problem with respect to the durability of catalyst that limits its wide application. Here, we present a new approach by exploring robust noncarbon Ti(0.7)Mo(0.3)O(2) used as a novel functionalized cocatalytic support for Pt. This approach is based on the novel nanostructure Ti(0.7)Mo(0.3)O(2) support with "electronic transfer mechanism" from Ti(0.7)Mo(0.3)O(2) to Pt that can modify the surface electronic structure of Pt, owing to a shift in the d-band center of the surface Pt atoms. Furthermore, another benefit of Ti(0.7)Mo(0.3)O(2) is the extremely high stability of Pt/Ti(0.7)Mo(0.3)O(2) during potential cycling, which is attributable to the strong metal/support interaction (SMSI) between Pt and Ti(0.7)Mo(0.3)O(2). This also enhances the inherent structural and chemical stability and the corrosion resistance of the TiO(2)-based oxide in acidic and oxidative environments. We also demonstrate that the ORR current densities generated using cocatalytic Pt/Ti(0.7)Mo(0.3)O(2) are respectively ~7- and 2.6-fold higher than those of commercial Pt/C and PtCo/C catalysts with the same Pt loading. This new approach opens a reliable path to the discovery advanced concept in designing new catalysts that can replace the traditional catalytic structure and motivate further research in the field.

  9. Measuring Substantial Reductions in Activity

    PubMed Central

    Schafer, Charles; Evans, Meredyth; Jason, Leonard A.; So, Suzanna; Brown, Abigail

    2015-01-01

    The case definitions for Myalgic Encephalomyelitis/chronic fatigue syndrome (ME/CFS), Myalgic Encephalomyelitis (ME), and chronic fatigue syndrome (CFS) each include a disability criterion requiring substantial reductions in activity in order to meet diagnostic criteria. Difficulties have been encountered in defining and operationalizing the substantial reduction disability criterion within these various illness definitions. The present study sought to relate measures of past and current activities in several domains including the SF-36, an objective measure of activity (e.g. actigraphy), a self-reported quality of life scale, and measures of symptom severity. Results of the study revealed that current work activities had the highest number of significant associations with domains such as the SF-36 subscales, actigraphy, and symptom scores. As an example, higher self-reported levels of current work activity were associated with better health. This suggests that current work related activities may provide a useful domain for helping operationalize the construct of substantial reductions in activity. PMID:25584524

  10. Reversible Hydrogenation of Carbon Dioxide to Formic Acid and Methanol: Lewis Acid Enhancement of Base Metal Catalysts.

    PubMed

    Bernskoetter, Wesley H; Hazari, Nilay

    2017-03-17

    New and sustainable energy vectors are required as a consequence of the environmental issues associated with the continued use of fossil fuels. H2 is a potential clean energy source, but as a result of problems associated with its storage and transport as a gas, chemical H2 storage (CHS), which involves the dehydrogenation of small molecules, is an attractive alternative. In principle, formic acid (FA, 4.4 wt % H2) and methanol (MeOH, 12.6 wt % H2) can be obtained renewably and are excellent prospective liquid CHS materials. In addition, MeOH has considerable potential both as a direct replacement for gasoline and as a fuel cell input. The current commercial syntheses of FA and MeOH, however, use nonrenewable feedstocks and will not facilitate the use of these molecules for CHS. An appealing option for the sustainable synthesis of both FA and MeOH, which could be implemented on a large scale, is the direct metal catalyzed hydrogenation of CO2. Furthermore, given that CO2 is a readily available, nontoxic and inexpensive source of carbon, it is expected that there will be economic and environmental benefits from using CO2 as a feedstock. One strategy to facilitate both the dehydrogenation of FA and MeOH and the hydrogenation of CO2 and H2 to FA and MeOH is to utilize a homogeneous transition metal catalyst. In particular, the development of catalysts based on first row transition metals, which are cheaper, and more abundant than their precious metal counterparts, is desirable. In this Account, we describe recent advances in the development of iron and cobalt systems for the hydrogenation of CO2 to FA and MeOH and the dehydrogenation of FA and MeOH and provide a brief comparison between precious metal and base metal systems. We highlight the different ligands that have been used to stabilize first row transition metal catalysts and discuss the use of additives to promote catalytic activity. In particular, the Account focuses on the crucial role that alkali metal Lewis

  11. MO-E-18C-05: Global Health Catalyst: A Novel Platform for Enhancing Access to Medical Physics Education and Research Excellence (AMPERE)

    SciTech Connect

    Ngwa, W; Moreau, M; Asana, L

    2014-06-15

    Purpose: To develop a platform for catalyzing collaborative global Cancer Care Education and Research (CaRE), with a prime focus on enhancing Access to Medical Physics Education and Research Excellence (AMPERE) Methods: An analysis of over 50 global health collaborations between partners in the U.S. and low and middle income countries (LMIC) in Africa was carried out to assess the models of collaborations in Education and Research and relative success. A survey was carried out with questions including: the nature of the collaboration, how it was initiated, impact of culture and other factors, and recommendations for catalyzing/enhancing such collaborations. An online platform called Global Health Catalyst was developed for enhancing AMPERE. Results: The analysis yielded three main models for global health collaborations with survey providing key recommendations on how to enhance such collaborations. Based on this, the platform was developed, and customized to allow Medical Physicists and other Radiation oncology (RadOnc) professionals interested in participating in Global health to readily do so e.g. teach an online course module, participate in training Medical Physicists or other RadOnc health professionals in LMIC, co-mentor students, residents or postdocs, etc. The growing list of features on the platform also include: a feature to enable people to easily find each other, form teams, operate more effectively as partners from different disciplines, institutions, nations and cultural backgrounds, share tools and technologies, obtain seed funding to develop curricula and/or embark upon new areas of investigation, and participate in humanitarian outreach: remote treatment planning assistance, and participation in virtual Chart Rounds, etc. Conclusion: The developed Global Health Catalyst platform could enable any Medical Physicist or RadoOnc professional interested in global health to readily participate in the Education/training of next generation Rad

  12. Clean Donor Oxidation Enhances the H2 Evolution Activity of a Carbon Quantum Dot-Molecular Catalyst Photosystem.

    PubMed

    Martindale, Benjamin C M; Joliat, Evelyne; Bachmann, Cyril; Alberto, Roger; Reisner, Erwin

    2016-08-01

    Carbon quantum dots (CQDs) are new-generation light absorbers for photocatalytic H2 evolution in aqueous solution, but the performance of CQD-molecular catalyst systems is currently limited by the decomposition of the molecular component. Clean oxidation of the electron donor by donor recycling prevents the formation of destructive radical species and non-innocent oxidation products. This approach allowed a CQD-molecular nickel bis(diphosphine) photocatalyst system to reach a benchmark lifetime of more than 5 days and a record turnover number of 1094±61 molH2  (molNi )(-1) for a defined synthetic molecular nickel catalyst in purely aqueous solution under AM1.5G solar irradiation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Enhanced high temperature performance of MgAl2O4-supported Pt-BaO lean NOx trap catalysts

    SciTech Connect

    Kwak, Ja Hun; Kim, Do Heui; Szanyi, Janos; Cho, Sung June; Peden, Charles HF

    2012-03-05

    The structural and chemical characteristics of Pt/BaO lean-NO{sub x} trap (LNT) catalysts supported on {gamma}-Al{sub 2}O{sub 3} and MgAl{sub 2}O{sub 4} are compared in this study. The Pt-BaO/MgAl{sub 2}O{sub 4} sample shows relatively low NO{sub x} uptake at temperatures below 300 C, and the temperature of maximum NO{sub x} uptake (T{sub max}) is shifted to 350 C in comparison to that of Pt-BaO/Al{sub 2}O{sub 3} (T{sub max} {approx}250 C). More importantly, the NO{sub x} uptake over the MgAl{sub 2}O{sub 4}-supported catalyst at 350 C is twice that of the alumina-based one. The shift toward the higher temperature NO{sub x} uptake is explained by the larger interfacial area between Pt and BaO, due to smaller Pt clusters as evidenced by TEM and Pt L3 EXAFS. In situ TR-XRD results demonstrate that the formation of a BaAl{sub 2}O{sub 4} phase in the BaO/MgAl{sub 2}O{sub 4} LNT catalyst occurs at a temperature about 100 C higher than on BaO/Al{sub 2}O{sub 3}, which may also represent a beneficial attribute of the BaO/MgAl{sub 2}O{sub 4} LNT with respect to catalyst stability.

  14. Enhanced catalytic degradation of ciprofloxacin with FeS2/SiO2 microspheres as heterogeneous Fenton catalyst: Kinetics, reaction pathways and mechanism.

    PubMed

    Diao, Zeng-Hui; Xu, Xiang-Rong; Jiang, Dan; Li, Gang; Liu, Jin-Jun; Kong, Ling-Jun; Zuo, Lin-Zi

    2017-04-05

    In this study, the application of FeS2/SiO2 microspheres as a catalyst to activate H2O2 for the degradation of ciprofloxacin (CIP) was systematically investigated. Results demonstrated that the presence of SiO2 microspheres on the surface of FeS2 could effectively make the reaction of aqueous Fe(2+) and H2O2 smoothly continuous by controlling the release of aqueous Fe(2+) from FeS2. Nearly 100% of CIP was degraded after 60min under the optimum conditions. A superior performance on the CIP degradation and high reusability of the catalyst was obtained in FeS2/SiO2 microspheres activated H2O2 system. A low concentration of ethylene diamine tetraacetie acid (EDTA) did positively affect the degradation rate of CIP. A synergetic effect between adsorption and oxidation processes contributed to the significant enhancement of CIP degradation. Seven oxidation intermediates were identified during the CIP degradation process, and the direct HO oxidation proved to be a main CIP degradation pathway. For degradation pathway of CIP, oxidation of piperazine ring would be its first step, followed by cleavage of the heterocyclic ring. Subsequently, the substitution, hydroxylation and decarboxylation processes occurred. This is the first report on the feasibility of FeS2/SiO2 microspheres activated H2O2 system for the enhanced degradation of CIP. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Enhanced photocatalytic efficiency of NiS/TiO{sub 2} composite catalysts using sunset yellow, an azo dye under day light illumination

    SciTech Connect

    Rajamanickam, D.; Dhatshanamurthi, P.; Shanthi, M.

    2015-01-15

    Highlights: • NiS/TiO{sub 2} was successfully synthesized by sol–gel method. • This new method of preparation gives a homogeneous dispersion of NiS on TiO{sub 2}. • Degradation activity of NiS/TiO{sub 2} is found to be more efficient than other catalysts. • Addition of oxidants enhances the degradation efficiency significantly. • COD measurements reveal the complete mineralization of dye molecules. • The catalyst is found to be reusable. - Abstract: To improve the solar light induced photocatalytic application performances of TiO{sub 2}, in this study, the NiS modified TiO{sub 2} composite photocatalysts with various ratios of NiS to TiO{sub 2} were prepared by sol–gel method. The catalyst was characterized by X-ray diffraction (XRD), high resolution scanning electron microscope (HR-SEM), high resolution transmission electron microscope (HR-TEM), energy dispersive spectra (EDS), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (B–E–T) surface area measurement methods. The photocatalytic activity of NiS/TiO{sub 2} was investigated for the degradation of sunset yellow (SY) in aqueous solution using solar light. The NiS/TiO{sub 2} is found to be more efficient than prepared TiO{sub 2} and TiO{sub 2}–P25 at pH 7 for the mineralization of SY. The effects of operational parameters such as the amount of photocatalyst, dye concentration and initial pH on photo mineralization of SY have been analyzed. The degradation was strongly enhanced in the presence of oxidants such as H{sub 3}K{sub 5}O{sub 18}S{sub 4} (Oxone), KIO{sub 4}, and KBrO{sub 3}. The mineralization of SY has been identified by COD measurements. The catalyst is found to be reusable.

  16. Reforming catalysts

    SciTech Connect

    Givens, E.N.; Plank, C.J.; Rosinski, E.J.

    1980-03-04

    Crystalline aluminosilicate zeolites are mixed with conventional reforming catalysts to produce new catalytic compositions with high catalytic activity and selectivity and excellent aging characteristics. These new catalytic compositions may be utilized alone or in conjunction with conventional reforming catalysts. The acidic activity of the total catalyst system is controlled within defined limits. When so controlled the utility of these catalyst systems in reforming hydrocarbon mixtures is to reduce the C1 and C2 concentrations in reformer gas product, while increasing the C3 and C4 concentrations and maintaining high liquid yield at high octane numbers.

  17. The Benzyl Ester Group of Amino Acid Monomers Enhances Substrate Affinity and Broadens the Substrate Specificity of the Enzyme Catalyst in Chemoenzymatic Copolymerization.

    PubMed

    Ageitos, Jose Manuel; Yazawa, Kenjiro; Tateishi, Ayaka; Tsuchiya, Kousuke; Numata, Keiji

    2016-01-11

    The chemoenzymatic polymerization of amino acid monomers by proteases involves a two-step reaction: the formation of a covalent acyl-intermediate complex between the protease and the carboxyl ester group of the monomer and the subsequent deacylation of the complex by aminolysis to form a peptide bond. Although the initiation with the ester group of the monomer is an important step, the influence of the ester group on the polymerization has not been studied in detail. Herein, we studied the effect of the ester groups (methyl, ethyl, benzyl, and tert-butyl esters) of alanine and glycine on the synthesis of peptides using papain as the catalyst. Alanine and glycine were selected as monomers because of their substantially different affinities toward papain. The efficiency of the polymerization of alanine and glycine benzyl esters was much greater than that of the other esters. The benzyl ester group therefore allowed papain to equally polymerize alanine and glycine, even though the affinity of alanine toward papain is substantially higher. The characterization of the copolymers of alanine and glycine in terms of the secondary structure and thermal properties revealed that the thermal stability of the peptides depends on the amino acid composition and resultant secondary structure. The current results indicate that the nature of the ester group drastically affects the polymerization efficiency and broadens the substrate specificity of the protease.

  18. Preparation and application of zirconium sulfate supported on SAPO-34 molecular sieve as solid acid catalyst for esterification

    SciTech Connect

    Xu, Dongyan Ma, Hong; Cheng, Fei

    2014-05-01

    Graphical abstract: - Highlights: • SAPO-34 supported zirconium sulfate solid acid catalyst was prepared. • Esterification of acetic acid with ethanol can be catalyzed by ZS/SAPO-34. • The hydration of ZS is vital to the acidic property and catalytic performance. • The ZS/SAPO-34 catalyst treated at 200 °C shows good reusability. - Abstract: Zirconium sulfate (ZS) was supported on SAPO-34 molecular sieve by using an incipient wetness impregnation method with zirconium sulfate as the precursor. The as-prepared catalysts were used as solid acid catalyst for esterification reaction of acetic acid with ethanol. The influence of calcination temperature on the acidic property, catalytic activity, and reusability of ZS/SAPO-34 catalysts were mainly investigated. FT-IR, SEM, EDS and TG analysis have been carried out to demonstrate the characteristics of ZS/SAPO-34 catalysts. It was found that the 30 wt%ZS/SAPO-34 catalysts display the property of superacid irrespective of calcination temperature. The ZS/SAPO-34 catalyst treated at 200 °C can enhance the interaction between the supported ZS and SAPO-34 and keep the catalyst remaining substantially active after several reaction cycles. However, further increasing calcination temperature will cause the transfer of ZS from hydrate to anhydrous phase, and thus the decrease of activity.

  19. Highly Stable and Active Catalyst for Sabatier Reactions

    NASA Technical Reports Server (NTRS)

    Hu, Jianli; Brooks, Kriston P.

    2012-01-01

    Highly active Ru/TiO2 catalysts for Sabatier reaction have been developed. The catalysts have shown to be stable under repeated shutting down/startup conditions. When the Ru/TiO2 catalyst is coated on the engineered substrate Fe-CrAlY felt, activity enhancement is more than doubled when compared with an identically prepared engineered catalyst made from commercial Degussa catalyst. Also, bimetallic Ru-Rh/TiO2 catalysts show high activity at high throughput.

  20. Generating power from cellulose in an alkaline fuel cell enhanced by methyl viologen as an electron-transfer catalyst

    NASA Astrophysics Data System (ADS)

    Hao, Miaoqing; Liu, Xianhua; Feng, Mengnan; Zhang, Pingping; Wang, Guangyi

    2014-04-01

    In this work, we developed a single-compartment direct cellulose alkaline fuel cell by using nickel foam as the anode and methyl viologen as an electron transfer catalyst. The maximum power density of the fuel cell at optimal conditions is 450 mW m-2. High-performance liquid chromatography detected short-chain aliphatic carboxylic acids in the oxidation products. Using common reed and red algae as fuels, the fuel cell achieved maximum power densities of 295 mW m-2 and 154 mW m-2, respectively.

  1. Synthesis of substantially monodispersed colloids

    NASA Technical Reports Server (NTRS)

    Klabunde, Kenneth J. (Inventor); Stoeva, Savka (Inventor); Sorensen, Christopher (Inventor)

    2003-01-01

    A method of forming ligated nanoparticles of the formula Y(Z).sub.x where Y is a nanoparticle selected from the group consisting of elemental metals having atomic numbers ranging from 21-34, 39-52, 57-83 and 89-102, all inclusive, the halides, oxides and sulfides of such metals, and the alkali metal and alkaline earth metal halides, and Z represents ligand moieties such as the alkyl thiols. In the method, a first colloidal dispersion is formed made up of nanoparticles solvated in a molar excess of a first solvent (preferably a ketone such as acetone), a second solvent different than the first solvent (preferably an organic aryl solvent such as toluene) and a quantity of ligand moieties; the first solvent is then removed under vacuum and the ligand moieties ligate to the nanoparticles to give a second colloidal dispersion of the ligated nanoparticles solvated in the second solvent. If substantially monodispersed nanoparticles are desired, the second dispersion is subjected to a digestive ripening process. Upon drying, the ligated nanoparticles may form a three-dimensional superlattice structure.

  2. Bimetallic Catalysts.

    ERIC Educational Resources Information Center

    Sinfelt, John H.

    1985-01-01

    Chemical reaction rates can be controlled by varying composition of miniscule clusters of metal atoms. These bimetallic catalysts have had major impact on petroleum refining, where work has involved heterogeneous catalysis (reacting molecules in a phase separate from catalyst.) Experimentation involving hydrocarbon reactions, catalytic…

  3. Bimetallic Catalysts.

    ERIC Educational Resources Information Center

    Sinfelt, John H.

    1985-01-01

    Chemical reaction rates can be controlled by varying composition of miniscule clusters of metal atoms. These bimetallic catalysts have had major impact on petroleum refining, where work has involved heterogeneous catalysis (reacting molecules in a phase separate from catalyst.) Experimentation involving hydrocarbon reactions, catalytic…

  4. The Addition of Graphene and Magnetite Materials in TiO2/CuO Catalyst for Enhancing Photosonocatalytic Performance and Reusability

    NASA Astrophysics Data System (ADS)

    Taufik, A.; Muzaki, A.; Saleh, R.

    2017-05-01

    In the present study, TiO2/CuO with the addition of graphene and magnetite materials were investigated as a catalyst for waste water removal through the photosonocatalytic process. TiO2/CuO/graphene and Fe3O4/TiO2/CuO/graphene were synthesized by using the sol-gel method. Their physical properties were characterized by using X-ray Diffraction, Fourier Transform Infra-red Spectroscopy, Thermogravimetric Analysis, Transmission Electron Microscope, and Breneur Emmet Teller (BET) surface area analyzer. The Photosonocatalytic activity was examined under visible light irradiation and 40 kHz ultrasound frequency with methyl orange (MO) as a model of organic pollutant. Compared to photocatalytic and sonocatalytic process, photosonocatalytic activity can improve the degradation process due to a synergistic effect between photocatalytic and sonocatalytic process at the same time. The addition of graphene materials can improve the charge carrier separation and prevent recombination electron and holes. Therefore, the photosonocatalytic performance increases significantly with the addition of graphene materials. The addition of magnetite materials is not only can enhance the photosonocatalytic performance but also can improve the separation process for reuse the catalyst. The photosonocatalytic mechanism was correlated with their physical properties and visible as well as ultrasound irradiation.

  5. Enhanced hydrogen evolution properties obtained by ultrasonic-cyclic voltammetry modification of C-supported PtCu thin film catalyst

    NASA Astrophysics Data System (ADS)

    Yi, Sha; Yang, Bin; Zhang, Zhan-Sheng

    2017-05-01

    Carbon-supported Pt-Cu (Pt-Cu/C) bimetallic catalyst was synthesized by Ion Beam Sputtering technology and subsequently annealed in vacuum and electrochemically etched by Ultrasonic-Cyclic Voltammetry (US-CV). Electrochemical measurements indicate that the sample was modified electrochemically by US-CV shows higher catalytic activity towards hydrogen evolution reaction than pure Pt/C. Scanning and transmission electron microscopy and electronic differential system analysis reveal that the surface of post-processed catalyst produced PtCu@Pt core-shell structure which increasing the efficiency of Pt. Transmission electron microscope analysis displays that on the surface of PtCu@Pt core-shell particles detects lattice compressive strain, the lattice compression variable is around 1.12%. X-ray photoelectron spectroscopy analysis confirms that the Pt4f7/2 binding energy of the post-processed PtCu/C is 71.10 eV, decreased by 0.2 eV compared to pure Pt/C (71.3 eV). It can be inferred that the enhancement of catalytic property attribute to the Cu atoms modified the geometric structure and electronic structure of the Pt atoms.

  6. Oxyhydrochlorination catalyst

    DOEpatents

    Taylor, Charles E.; Noceti, Richard P.

    1992-01-01

    An improved catalyst and method for the oxyhydrochlorination of methane is disclosed. The catalyst includes a pyrogenic porous support on which is layered as active material, cobalt chloride in major proportion, and minor proportions of an alkali metal chloride and of a rare earth chloride. On contact of the catalyst with a gas flow of methane, HCl and oxygen, more than 60% of the methane is converted and of that converted more than 40% occurs as monochloromethane. Advantageously, the monochloromethane can be used to produce gasoline boiling range hydrocarbons with the recycle of HCl for further reaction. This catalyst is also of value for the production of formic acid as are analogous catalysts with lead, silver or nickel chlorides substituted for the cobalt chloride.

  7. Enhancement of (stereo)selectivity in dynamic kinetic resolution using a core-shell nanozeolite@enzyme as a bi-functional catalyst.

    PubMed

    Wang, Wanlu; Li, Xiang; Wang, Zhoujun; Tang, Yi; Zhang, Yahong

    2014-08-28

    A core-shell nanozeolite@enzyme bi-functional catalyst is constructed, which greatly improves selectivity and stereoselectivity of products in dynamic kinetic resolution of aromatic secondary alcohols compared with mixed catalysts, especially those involving small acyl donors.

  8. Liquid-phase growth of platinum nanoparticles on molybdenum trioxide nanosheets: an enhanced catalyst with intrinsic peroxidase-like catalytic activity.

    PubMed

    Wang, Yixian; Zhang, Xiao; Luo, Zhimin; Huang, Xiao; Tan, Chaoliang; Li, Hai; Zheng, Bing; Li, Bing; Huang, Ying; Yang, Jian; Zong, Yun; Ying, Yibin; Zhang, Hua

    2014-11-07

    A facile method for the synthesis of metal nanostructure-decorated two-dimensional (2D) semiconductor nanosheets was developed. The solution-processable molybdenum trioxide (MoO3) nanosheet was used as a template for direct liquid-phase growth of platinum nanoparticles (Pt NPs) under ambient conditions. Results show that the Pt NPs with sizes of 1-3 nm were uniformly grown on the MoO3 surface. Importantly, the Pt-MoO3 hybrid nanomaterial exhibits an enhanced peroxidase-like catalytic activity compared to the MoO3 nanosheet, Pt NPs, and their physical mixture under the same conditions. As a proof-of-concept application, the Pt-MoO3 hybrid nanomaterial was used as a high-efficiency peroxidase-mimic for ultrasensitive colorimetric detection of glucose in serum samples. This work provides a promising strategy for design and development of biomimetic catalysts by smart assembly of different dimensional nanomaterials.

  9. Catalysts for Dehydrogenation of ammonia boranes

    SciTech Connect

    Heinekey, Dennis M.

    2009-10-31

    Several effective homogeneous catalysts for the dehydrogenation of amine boranes have been developed. The best catalyst uses an iridium complex, and is capable of dehydrogenating H3NBH3 (AB) and CH3NH2BH3 (MeAB) at comparable rates. Thermodynamic measurements using this catalyst demonstrate that the dehydrogenation of AB and MeAB is substantially exothermic, which has important implications for regeneration.

  10. Carbon-supported bimetallic Pd–Fe catalysts for vapor-phase hydrodeoxygenation of guaiacol

    SciTech Connect

    Sun, Junming; Karim, Ayman M.; Zhang, He; Kovarik, Libor; Li, Xiaohong Shari; Hensley, Alyssa J.; McEwen, Jean-Sabin; Wang, Yong

    2013-10-01

    Abstract Carbon supported metal catalysts (Cu/C, Fe/C, Pd/C, Pt/C, PdFe/C and Ru/C) have been prepared, characterized and tested for vapor-phase hydrodeoxygenation (HDO) of guaiacol (GUA) at atmospheric pressure. Phenol was the major intermediate on all catalysts. Over the noble metal catalysts saturation of the aromatic ring was the major pathway observed at low temperature (250 °C), forming predominantly cyclohexanone and cyclohexanol. Substantial ring opening reaction was observed on Pt/C and Ru/C at higher reaction temperatures (e.g., 350 °C). Base metal catalysts, especially Fe/C, were found to exhibit high HDO activity without ring-saturation or ring-opening with the main products being benzene, phenol along with small amounts of cresol, toluene and trimethylbenzene (TMB). A substantial enhancement in HDO activity was observed on the PdFe/C catalysts. Compared with Fe/C, the yield to oxygen-free aromatic products (i.e., benzene/toluene/TMB) on PdFe/C increased by a factor of four at 350 °C, and by approximately a factor of two (83.2% versus 43.3%) at 450 °C. The enhanced activity of PdFe/C is attributed to the formation of PdFe alloy as evidenced by STEM, EDS and TPR.

  11. Nanowire Morphology of Mono- and Bidoped α-MnO2 Catalysts for Remarkable Enhancement in Soot Oxidation.

    PubMed

    Jampaiah, Deshetti; Velisoju, Vijay Kumar; Venkataswamy, Perala; Coyle, Victoria E; Nafady, Ayman; Reddy, Benjaram M; Bhargava, Suresh K

    2017-09-27

    In the present work, nanowire morphologies of α-MnO2, cobalt monodoped α-MnO2, Cu and Co bidoped α-MnO2, and Ni and Co bidoped α-MnO2 samples were prepared by a facile hydrothermal synthesis. The structural, morphological, surface, and redox properties of all the as-prepared samples were investigated by various characterization techniques, namely, scanning electron microscopy (SEM), transmission and high resolution electron microscopy (TEM and HR-TEM), powder X-ray diffraction (XRD), N2 sorption surface area measurements, X-ray photoelectron spectroscopy (XPS), hydrogen-temperature-programmed reduction (H2-TPR), and oxygen-temperature-programmed desorption (O2-TPD). The soot oxidation performance was found to be significantly improved via metal mono- and bidoping. In particular, Cu and Co bidoped α-MnO2 nanowires showed a remarkable improvement in soot oxidation performance, with its T50 (50% soot conversion) values of 279 and 431 °C under tight and loose contact conditions, respectively. The soot combustion activation energy for the Cu and Co bidoped MnO2 nanowires is 121 kJ/mol. The increased oxygen vacancies, greater number of active sites, facile redox behavior, and strong synergistic interaction were the key factors for the excellent catalytic activity. The longevity of Cu and Co bidoped α-MnO2 nanowires was analyzed, and it was found that the Cu/Co bidoped α-MnO2 nanowires were highly stable after five successive cycles and showed an insignificant decrease in soot oxidation activity. Furthermore, the HR-TEM analysis of a spent catalyst after five cycles indicated that the (310) crystal plane of α-MnO2 interacts with the soot particles; therefore, we can assume that more-reactive exposed surfaces positively affect the reaction of soot oxidation. Thus, the Cu and Co bidoped α-MnO2 nanowires provide promise as a highly effective alternative to precious metal based automotive catalysts.

  12. Catalyst mixtures

    DOEpatents

    Masel, Richard I.; Rosen, Brian A.

    2017-02-14

    Catalysts that include at least one catalytically active element and one helper catalyst can be used to increase the rate or lower the overpotential of chemical reactions. The helper catalyst can simultaneously act as a director molecule, suppressing undesired reactions and thus increasing selectivity toward the desired reaction. These catalysts can be useful for a variety of chemical reactions including, in particular, the electrochemical conversion of CO.sub.2 or formic acid. The catalysts can also suppress H.sub.2 evolution, permitting electrochemical cell operation at potentials below RHE. Chemical processes and devices using the catalysts are also disclosed, including processes to produce CO, OH.sup.-, HCO.sup.-, H.sub.2CO, (HCO.sub.2).sup.-, H.sub.2CO.sub.2, CH.sub.3OH, CH.sub.4, C.sub.2H.sub.4, CH.sub.3CH.sub.2OH, CH.sub.3COO.sup.-, CH.sub.3COOH, C.sub.2H.sub.6, O.sub.2, H.sub.2, (COOH).sub.2, or (COO.sup.-).sub.2, and a specific device, namely, a CO.sub.2 sensor.

  13. Assessment of hydrothermal pretreatment of various lignocellulosic biomass with CO2 catalyst for enhanced methane and hydrogen production.

    PubMed

    Eskicioglu, Cigdem; Monlau, Florian; Barakat, Abdellatif; Ferrer, Ivet; Kaparaju, Prasad; Trably, Eric; Carrère, Hélène

    2017-09-01

    Hydrothermal pretreatment of five lignocellulosic substrates (i.e. wheat straw, rice straw, biomass sorghum, corn stover and Douglas fir bark) were conducted in the presence of CO2 as a catalyst. To maximize disintegration and conversion into bioenergy (methane and hydrogen), pretreatment temperatures and subsequent pressures varied with a range of 26-175 °C, and 25-102 bars, respectively. Among lignin, cellulose and hemicelluloses, hydrothermal pretreatment caused the highest reduction (23-42%) in hemicelluloses while delignification was limited to only 0-12%. These reductions in structural integrity resulted in 20-30% faster hydrolysis rates during anaerobic digestion for the pretreated substrates of straws, sorghum, and corn stover while Douglas fir bark yielded 172% faster hydrolysis/digestion due to its highly refractory nature in the control. Furans and phenolic compounds formed in the pretreated hydrolyzates were below the inhibitory levels for methane and hydrogen production which had a range of 98-340 ml CH4/g volatile solids (VS) and 5-26 ml H2/g VS, respectively. Results indicated that hydrothermal pretreatment is able to accelerate the rate of biodegradation without generating high levels of inhibitory compounds while showing no discernible effect on ultimate biodegradation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Enhanced performance and stability of high temperature proton exchange membrane fuel cell by incorporating zirconium hydrogen phosphate in catalyst layer

    NASA Astrophysics Data System (ADS)

    Barron, Olivia; Su, Huaneng; Linkov, Vladimir; Pollet, Bruno G.; Pasupathi, Sivakumar

    2015-03-01

    Zirconium hydrogen phosphate (ZHP) together with polytetrafluoroethylene (PTFE) polymer binder is incorporated into the catalyst layers (CLs) of ABPBI (poly(2,5-benzimidazole))-based high temperature polymer electrolyte membrane fuel cell (HT-PEMFCs) to improve its performance and durability. The influence of ZHP content (normalised with respect to dry PTFE) on the CL properties are structurally characterised by scanning electron microscopy (SEM) and mercury intrusion porosimetry. Electrochemical analyses of the resultant membrane electrode assemblies (MEAs) are performed by recording polarisation curves and impedance spectra at 160 °C, ambient pressure and humidity. The result show that a 30 wt.% ZHP/PTFE content in the CL is optimum for improving fuel cell performance, the resultant MEA delivers a peak power of 592 mW cm-2 at a cell voltage of 380 mV. Electrochemical impedance spectra (EIS) indicate that 30% ZHP in the CL can increase the proton conductivity compared to the pristine PTFE-gas diffusion electrode (GDE). A short term stability test (∼500 h) on the 30 wt.% ZHP/PTFE-GDE shows a remarkable high durability with a degradation rate as low as ∼19 μV h-1 at 0.2 A cm-2, while 195 μV h-1 was obtained for the pristine GDE.

  15. One-step synthesis of Fe–N–S-tri-doped TiO{sub 2} catalyst and its enhanced visible light photocatalytic activity

    SciTech Connect

    Cheng, Xiuwen; Yu, Xiujuan; Xing, Zipeng

    2012-11-15

    Graphical abstract: FeNS-TiO{sub 2} exhibits stronger SPS response than that of pure TiO{sub 2}, indicating that the FeNS-TiO{sub 2} should have a higher separation rates of photoinduced charge carriers. Further, for the sample FeNS-TiO{sub 2} a broad shoulder SPS response can be seen at the wavelength range from 390 to 550 nm, suggesting that the light absorption in visible region of FeNS-TiO{sub 2} was greatly improved, which is beneficial to the enhancement of photocatalytic activity. Display Omitted Highlights: ► FeNS-TiO{sub 2} catalyst has been synthesized in the presence of ammonium ferrous sulfate. ► The light absorption edge of FeNS-TiO{sub 2} catalyst was red-shifted to visible region. ► The separation efficiency of photoinduced charge carriers of FeNS-TiO{sub 2} was improved. ► The activity enhanced mechanism of FeNS-TiO{sub 2} was discussed in detail. -- Abstract: Fe–N–S-tridoped TiO{sub 2} was synthesized through simple one step sol–gel reactions in the presence of ammonium ferrous sulfate. The resulting materials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, diffuse reflectance spectrum and surface photovoltage spectroscopy. Results revealed that Fe and S were incorporated into the lattice of TiO{sub 2} by substituting for some Ti atoms and N for O atoms in the lattice of TiO{sub 2}. Tri-doping with Fe, N and S could inhibit the phase transformation of TiO{sub 2} from anatase to rutile, restrain the growth of crystallite sizes, extended the light absorption into the visible region and separate photoinduced charge carriers. The visible photocatalytic activity of Fe–N–S-tridoped TiO{sub 2} was higher than that of N-TiO{sub 2} and P25 TiO{sub 2}. The enhanced photocatalytic activity was attributed to the small crystallite size, high crystallinity, the intense light absorption in visible region, narrow band gap and high separation efficiency of photoinduced charge carriers.

  16. Theoretical substantiation of biological efficacy enhancement for β-delayed particle decay {sup 9}C beam: A Monte Carlo study in combination with analysis with the local effect model approach

    SciTech Connect

    Tian, Liheng; Yan, Yuanlin; Ma, Yuanyuan; Huang, Qiyan; Li, Qiang Liu, Xinguo; Dai, Zhongying; Fu, Tingyan; He, Pengbo

    2016-03-15

    Purpose: To improve the efficacy of heavy ion therapy, β-delayed particle decay {sup 9}C beam as a double irradiation source for cancer therapy has been proposed. The authors’ previous experiment showed that relative biological effectiveness (RBE) values at the depths around the Bragg peak of a {sup 9}C beam were enhanced and compared to its stable counterpart {sup 12}C beam. The purpose of this study was to explore the nature of the biological efficacy enhancement theoretically. Methods: A Monte Carlo simulation study was conducted in this study. First a simplified cell model was established so as to form a tumor tissue. Subsequently, the tumor tissue was imported into the Monte Carlo simulation software package GATE and then the tumor cells were virtually irradiated with comparable {sup 9}C and {sup 12}C beams, respectively, in the simulations. The transportation and particle deposition data of the {sup 9}C and {sup 12}C beams, derived from the GATE simulations, were analyzed with the authors’ local effect model implementation so as to deduce cell survival fractions. Results: The particles emitted from the decay process of deposited {sup 9}C particles around a cell nucleus increased the dose delivered to the nucleus and elicited clustered damages around the secondary particles’ trajectories. Therefore, compared to the {sup 12}C beam, the RBE value of the {sup 9}C beam increased at the depths around their Bragg peaks. Conclusions: Collectively, the increased local doses and clustered damages due to the decayed particles emitted from deposited {sup 9}C particles led to the RBE enhancement in contrast with the {sup 12}C beam. Thus, the enhanced RBE effect of a {sup 9}C beam for a simplified tumor model was shown theoretically in this study.

  17. Binary ferrihydrite catalysts

    DOEpatents

    Huffman, G.P.; Zhao, J.; Feng, Z.

    1996-12-03

    A method of preparing a catalyst precursor comprises dissolving an iron salt and a salt of an oxoanion forming agent, in water so that a solution of the iron salt and oxoanion forming agent salt has a ratio of oxoanion/Fe of between 0.0001:1 to 0.5:1. Next is increasing the pH of the solution to 10 by adding a strong base followed by collecting of precipitate having a binary ferrihydrite structure. A binary ferrihydrite catalyst precursor is also prepared by dissolving an iron salt in water. The solution is brought to a pH of substantially 10 to obtain ferrihydrite precipitate. The precipitate is then filtered and washed with distilled water and subsequently admixed with a hydroxy carboxylic acid solution. The admixture is mixed/agitated and the binary ferrihydrite precipitate is then filtered and recovered. 3 figs.

  18. Binary ferrihydrite catalysts

    DOEpatents

    Huffman, Gerald P.; Zhao, Jianmin; Feng, Zhen

    1996-01-01

    A method of preparing a catalyst precursor comprises dissolving an iron salt and a salt of an oxoanion forming agent, in water so that a solution of the iron salt and oxoanion forming agent salt has a ratio of oxoanion/Fe of between 0.0001:1 to 0.5:1. Next is increasing the pH of the solution to 10 by adding a strong base followed by collecting of precipitate having a binary ferrihydrite structure. A binary ferrihydrite catalyst precursor is also prepared by dissolving an iron salt in water. The solution is brought to a pH of substantially 10 to obtain ferrihydrite precipitate. The precipitate is then filtered and washed with distilled water and subsequently admixed with a hydroxy carboxylic acid solution. The admixture is mixed/agitated and the binary ferrihydrite precipitate is then filtered and recovered.

  19. Strengthening leadership as a catalyst for enhanced patient safety culture: a repeated cross-sectional experimental study

    PubMed Central

    Kristensen, Solvejg; Christensen, Karl Bang; Jaquet, Annette; Møller Beck, Carsten; Sabroe, Svend; Bartels, Paul; Mainz, Jan

    2016-01-01

    Objectives Current literature emphasises that clinical leaders are in a position to enable a culture of safety, and that the safety culture is a performance mediator with the potential to influence patient outcomes. This paper aims to investigate staff's perceptions of patient safety culture in a Danish psychiatric department before and after a leadership intervention. Methods A repeated cross-sectional experimental study by design was applied. In 2 surveys, healthcare staff were asked about their perceptions of the patient safety culture using the 7 patient safety culture dimensions in the Safety Attitudes Questionnaire. To broaden knowledge and strengthen leadership skills, a multicomponent programme consisting of academic input, exercises, reflections and discussions, networking, and action learning was implemented among the clinical area level leaders. Results In total, 358 and 325 staff members participated before and after the intervention, respectively. 19 of the staff members were clinical area level leaders. In both surveys, the response rate was >75%. The proportion of frontline staff with positive attitudes improved by ≥5% for 5 of the 7 patient safety culture dimensions over time. 6 patient safety culture dimensions became more positive (increase in mean) (p<0.05). Frontline staff became more positive on all dimensions except stress recognition (p<0.05). For the leaders, the opposite was the case (p<0.05). Staff leaving the department after the first measurement had rated job satisfaction lower than the staff staying on (p<0.05). Conclusions The improvements documented in the patient safety culture are remarkable, and imply that strengthening the leadership can act as a significant catalyst for patient safety culture improvement. Further studies using a longitudinal study design are recommended to investigate the mechanism behind leadership's influence on patient safety culture, sustainability of improvements over time, and the association of change

  20. Strategy to eliminate catalyst hot-spots in the partial oxidation of methane: enhancing its activity for direct hydrogen production by reducing the reactivity of lattice oxygen.

    PubMed

    Wen, Cun; Liu, Yi; Guo, Yun; Wang, Yanqin; Lu, Guanzhong

    2010-02-14

    Hydrogen can be produced over Er(2)O(3) in methane oxidation (oxygen/methane = 26). The reactivity of lattice oxygen in the catalyst plays a main role in the conversion of surface hydroxyl species to hydrogen or water. Adding a rare earth element into a catalyst can reduce the reactivity of lattice oxygen, resulting in increased hydrogen production, to eliminate catalyst hot-spots.

  1. Enhancing Care for Older People Living in Nursing Homes in Rural Australia Using Action Learning as a Catalyst for Change

    ERIC Educational Resources Information Center

    Penney, Wendy; Meyer, Julienne; Cash, Penny; Clinnick, Lisa; Martin, Louise

    2017-01-01

    The implementation of action learning workshops in three nursing homes in rural Victoria, Australia has been critical in the re-visioning of how care can be enhanced for residents. The workshops were designed with the intent of improving quality of care for residents by providing health care staff with opportunities to learn together and effect…

  2. Tethered catalysts for the hydration of carbon dioxide

    SciTech Connect

    Valdez, Carlos A; Satcher, Jr., Joe H; Aines, Roger D; Wong, Sergio E; Baker, Sarah E; Lightstone, Felice C; Stolaroff, Joshuah K

    2014-11-04

    A system is provided that substantially increases the efficiency of CO.sub.2 capture and removal by positioning a catalyst within an optimal distance from the air-liquid interface. The catalyst is positioned within the layer determined to be the highest concentration of carbon dioxide. A hydrophobic tether is attached to the catalyst and the hydrophobic tether modulates the position of the catalyst within the liquid layer containing the highest concentration of carbon dioxide.

  3. Reforming catalyst

    SciTech Connect

    Baird, W.C. Jr.; Swan, G.A.

    1991-11-19

    This patent describes a catalyst useful for reforming a naphtha feed at high severity reforming conditions. It comprises the metals, platinum, rhenium and iridium on a refractory porous inorganic oxide support, the support consisting essentially of alumina, wherein the concentration by weight of each of the metals platinum and rhenium is at least 0.1 percent and iridium at least 0.15 percent and at least one of the metals is present in a concentration of at least 0.3 percent, and the sum-total; concentration of the metals is greater than 0.9 percent, and wherein each catalyst particle contains all three of the metals platinum, rhenium and iridium. This patent also describes this composition wherein the catalyst contains from about 0.1 percent to about 3 percent of a halogen and from about 0.05 percent to about 0.02 percent sulfur.

  4. Enhanced E/Z Isomerization of (All-E)-lycopene by Employing Iron(III) Chloride as a Catalyst.

    PubMed

    Honda, Masaki; Kawana, Takahiro; Takehara, Munenori; Inoue, Yoshinori

    2015-07-01

    Catalytic isomerization of (all-E)-lycopene to Z-isomers using iron(III) chloride was investigated and optimized under various conditions of solvents, concentrations of iron(III) chloride, and reaction temperatures. The total contents of Z-isomers converted were higher in the order of CH2 Cl2 (78.4%) > benzene (61.4%) > acetone (51.5%) > ethyl acetate (50.8%) at 20 °C for 3 h using 1.0 × 10(-3) mg/mL iron(III) chloride for 0.1 mg/mL (all-E)-lycopene. However, the decomposition of lycopene was markedly accelerated in CH2 Cl2 : the remaining lycopene after the reaction for 3 h and 12 h was only 79.4% and 47.5%, respectively. As the concentration of catalyst increased in acetone, the Z-isomerization ratio of lycopene increased to more than 80%, followed by rapid degradation of lycopene to undetectable levels using >4.0 × 10(-3) mg/mL iron(III) chloride with the above concentration of (all-E)-lycopene. Finally, greater isomerization (79.9%) was attained at 60 °C in acetone for 3 h in the presence of 1.0 × 10(-3) mg/mL iron(III) chloride, largely without decomposition of lycopene (remaining ratio of total amount of lycopene isomers after the reaction, 96.5%). As iron(III) chloride has found general use as a food additive for iron fortification and acetone is also widely used in the food field, this method can be applied to the food and beverage processing industry. The dietary intake of lycopene, a natural red pigment found in brightly colored vegetables and fruits such as tomatoes and watermelons, has been reported to lower the risk of some diseases, including cancer. Lycopene molecules occur naturally in a long and “straight” shape, but on the other hand lycopene molecules with “bent” forms are highly absorbed by living cells, and showed good antioxidant activity. This study has demonstrated the efficient production of the “bent” lycopene using ionic iron as an accelerator, which is often contained in nutritional supplements. © 2015 Institute of Food

  5. Fluorination process using catalyst

    DOEpatents

    Hochel, Robert C.; Saturday, Kathy A.

    1985-01-01

    A process for converting an actinide compound selected from the group consisting of uranium oxides, plutonium oxides, uranium tetrafluorides, plutonium tetrafluorides and mixtures of said oxides and tetrafluorides, to the corresponding volatile actinide hexafluoride by fluorination with a stoichiometric excess of fluorine gas. The improvement involves conducting the fluorination of the plutonium compounds in the presence of a fluoride catalyst selected from the group consisting of CoF.sub.3, AgF.sub.2 and NiF.sub.2, whereby the fluorination is significantly enhanced. The improvement also involves conducting the fluorination of one of the uranium compounds in the presence of a fluoride catalyst selected from the group consisting of CoF.sub.3 and AgF.sub.2, whereby the fluorination is significantly enhanced.

  6. Fluorination process using catalysts

    DOEpatents

    Hochel, R.C.; Saturday, K.A.

    1983-08-25

    A process is given for converting an actinide compound selected from the group consisting of uranium oxides, plutonium oxides, uranium tetrafluorides, plutonium tetrafluorides and mixtures of said oxides and tetrafluorides, to the corresponding volatile actinide hexafluoride by fluorination with a stoichiometric excess of fluorine gas. The improvement involves conducting the fluorination of the plutonium compounds in the presence of a fluoride catalyst selected from the group consisting of CoF/sub 3/, AgF/sub 2/ and NiF/sub 2/, whereby the fluorination is significantly enhanced. The improvement also involves conducting the fluorination of one of the uranium compounds in the presence of a fluoride catalyst selected from the group consisting of CoF/sub 3/ and AgF/sub 2/, whereby the fluorination is significantly enhanced.

  7. 77 FR 34785 - Substantial Business Activities

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-12

    ... Internal Revenue Service 26 CFR Part 1 RIN 1545-BK86 Substantial Business Activities AGENCY: Internal... regulations regarding whether a foreign corporation has substantial business activities in a foreign country... substantial business activities in a foreign country, the Internal Revenue Service (IRS) and the Department...

  8. 77 FR 34887 - Substantial Business Activities

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-12

    ... Internal Revenue Service 26 CFR Part 1 RIN 1545-BK85 Substantial Business Activities AGENCY: Internal... substantial business activities in a foreign country. These regulations affect certain domestic corporations... whether a foreign corporation has substantial business activities in a foreign country for purposes...

  9. Enhanced anti-Diastereo- and Enantioselectivity in Alcohol Mediated Carbonyl Crotylation Using an Isolable Single Component Iridium Catalyst

    PubMed Central

    Gao, Xin; Townsend, Ian A.; Krische, Michael J.

    2011-01-01

    The cyclometallated iridium complex (S)-I derived from [Ir(cod)Cl]2, 4-cyano-3-nitrobenzoic acid, allyl acetate and (S)-SEGPHOS is conveniently isolated by precipitation or through conventional silica gel flash chromatography. This single component precatalyst allows alcohol mediated carbonyl crotylations to be performed at significantly lower temperature, resulting in enhanced levels of anti-diastereo- and enantioselectivity. Most significantly, the chromatographically isolated precatalyst (S)-I enables carbonyl crotylations that are not possible under previously reported conditions involving in situ generation of (S)-I. PMID:21375283

  10. Catalyst activator

    DOEpatents

    McAdon, Mark H.; Nickias, Peter N.; Marks, Tobin J.; Schwartz, David J.

    2001-01-01

    A catalyst activator particularly adapted for use in the activation of metal complexes of metals of Group 3-10 for polymerization of ethylenically unsaturated polymerizable monomers, especially olefins, comprising two Group 13 metal or metalloid atoms and a ligand structure including at least one bridging group connecting ligands on the two Group 13 metal or metalloid atoms.

  11. Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

    NASA Astrophysics Data System (ADS)

    Ahmed, Nesreen S.; Menzel, Robert; Wang, Yifan; Garcia-Gallastegui, Ainara; Bawaked, Salem M.; Obaid, Abdullah Y.; Basahel, Sulaiman N.; Mokhtar, Mohamed

    2017-02-01

    Two efficient catalyst based on CuAl and CoAl layered double hydroxides (LDHs) supported on graphene oxide (GO) for the carbon-carbon coupling (Classic Ullmann Homocoupling Reaction) are reported. The pure and hybrid materials were synthesised by direct precipitation of the LDH nanoparticles onto GO, followed by a chemical, structural and physical characterisation by electron microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area measurements and X-ray photoelectron spectroscopy (XPS). The GO-supported and unsupported CuAl-LDH and CoAl-LDH hybrids were tested over the Classic Ullman Homocoupling Reaction of iodobenzene. In the current study CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary and two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH.

  12. Sabatier Catalyst Poisoning Investigation

    NASA Technical Reports Server (NTRS)

    Nallette, Tim; Perry, Jay; Abney, Morgan; Knox, Jim; Goldblatt, Loel

    2013-01-01

    The Carbon Dioxide Reduction Assembly (CRA) on the International Space Station (ISS) has been operational since 2010. The CRA uses a Sabatier reactor to produce water and methane by reaction of the metabolic CO2 scrubbed from the cabin air and the hydrogen byproduct from the water electrolysis system used for metabolic oxygen generation. Incorporating the CRA into the overall air revitalization system has facilitated life support system loop closure on the ISS reducing resupply logistics and thereby enhancing longer term missions. The CRA utilizes CO2 which has been adsorbed in a 5A molecular sieve within the Carbon Dioxide Removal Assembly, CDRA. There is a potential of compounds with molecular dimensions similar to, or less than CO2 to also be adsorbed. In this fashion trace contaminants may be concentrated within the CDRA and subsequently desorbed with the CO2 to the CRA. Currently, there is no provision to remove contaminants prior to entering the Sabatier catalyst bed. The risk associated with this is potential catalyst degradation due to trace organic contaminants in the CRA carbon dioxide feed acting as catalyst poisons. To better understand this risk, United Technologies Aerospace System (UTAS) has teamed with MSFC to investigate the impact of various trace contaminants on the CRA catalyst performance at relative ISS cabin air concentrations and at about 200/400 times of ISS concentrations, representative of the potential concentrating effect of the CDRA molecular sieve. This paper summarizes our initial assessment results.

  13. Autothermal reforming catalyst having perovskite structure

    DOEpatents

    Krumpel, Michael; Liu, Di-Jia

    2009-03-24

    The invention addressed two critical issues in fuel processing for fuel cell application, i.e. catalyst cost and operating stability. The existing state-of-the-art fuel reforming catalyst uses Rh and platinum supported over refractory oxide which add significant cost to the fuel cell system. Supported metals agglomerate under elevated temperature during reforming and decrease the catalyst activity. The catalyst is a perovskite oxide or a Ruddlesden-Popper type oxide containing rare-earth elements, catalytically active firs row transition metal elements, and stabilizing elements, such that the catalyst is a single phase in high temperature oxidizing conditions and maintains a primarily perovskite or Ruddlesden-Popper structure under high temperature reducing conditions. The catalyst can also contain alkaline earth dopants, which enhance the catalytic activity of the catalyst, but do not compromise the stability of the perovskite structure.

  14. Enhancing the power generation in microbial fuel cells with effective utilization of goethite recovered from mining mud as anodic catalyst.

    PubMed

    Jadhav, Dipak A; Ghadge, Anil N; Ghangrekar, Makarand M

    2015-09-01

    Catalytic effect of goethite recovered from iron-ore mining mud was studied in microbial fuel cells (MFCs). Characterization of material recovered from mining mud confirms the recovery of iron oxide as goethite. Heat treated goethite (550 °C) and untreated raw goethite were coated on stainless-steel anode of MFC-1 and MFC-2, respectively; whereas, unmodified stainless-steel anode was used in MFC-3 (control). Fivefold increment in power was obtained in MFC-1 (17.1 W/m(3) at 20 Ω) than MFC-3 (3.5 W/m(3)). MFC with raw goethite coated anode also showed enhanced power (11 W/m(3)). Higher Coulombic efficiency (34%) was achieved in MFC-1 than control MFC-3 (13%). Decrease in mass-transport losses and higher redox current during electrochemical analyses support improved electron transfer with the use of goethite on anode. Cheaper goethite coating kinetically accelerates the electron transfer between bacteria and anode, proving to be a novel approach for enhancing the electricity generation along with organic matter removal in MFC.

  15. Biofouling inhibition and enhancing performance of microbial fuel cell using silver nano-particles as fungicide and cathode catalyst.

    PubMed

    Noori, Md T; Jain, Sumat C; Ghangrekar, M M; Mukherjee, C K

    2016-11-01

    Morphological analysis of biofouling developed on cathode surface in an air-cathode microbial fuel cell (MFC) was performed. For sustaining power production and enhancing Coulombic efficiency (CE) of MFC, studies were conducted to inhibit cathode biofouling using different loadings of silver nanoparticles (Ag-NPs) with 5% and 10% Ag in carbon black powder. In MFC without using Ag-NPs in cathode (MFC-C), cathode biofouling increased the charge transfer resistance (Rct) from 1710Ω.cm(2) to 2409Ω.cm(2), and reduced CE by 32%; whereas in MFC with 10% Ag in cathode Rct increased by only 5%. Power density of 7.9±0.5W/m(3) in MFC using 5% Ag and 9.8±0.3W/m(3) in MFC using 10% Ag in cathode was 4.6 and 5.7-folds higher than MFC-C. These results suggest that the Ag-NPs effectively inhibit the fungal biofouling on cathode surface of MFCs and enhanced the power recovery and CE by improving cathode kinetics.

  16. Characterizing substrate–surface interactions on alumina-supported metal catalysts by dynamic nuclear polarization-enhanced double-resonance NMR spectroscopy [Characterizing substrate-surface interactions on alumina supported metal catalysts by DNP-enhanced double-resonance NMR spectroscopy

    DOE PAGES

    Perras, Frederic A.; Padmos, J. Daniel; Johnson, Robert L.; ...

    2017-01-23

    The characterization of nanometer-scale interactions between carbon-containing substrates and alumina surfaces is of paramount importance to industrial and academic catalysis applications, but it is also very challenging. Here, we demonstrate that dynamic nuclear polarization surface-enhanced NMR spectroscopy (DNP SENS) allows the unambiguous description of the coordination geometries and conformations of the substrates at the alumina surface through high-resolution measurements of 13C–27Al distances. We apply this new technique to elucidate the molecular-level geometry of 13C-enriched methionine and natural abundance poly(vinyl alcohol) adsorbed on γ-Al2O3-supported Pd catalysts, and we support these results with element-specific X-ray absorption near-edge measurements. Furthermore, this work clearlymore » demonstrates a surprising bimodal coordination of methionine at the Pd–Al2O3 interface.« less

  17. A Non-sulfided flower-like Ni-PTA Catalyst that Enhances the Hydrotreatment Efficiency of Plant Oil to Produce Green Diesel

    PubMed Central

    Liu, Jing; Chen, Pan; Deng, Lihong; He, Jing; Wang, Luying; Rong, Long; Lei, Jiandu

    2015-01-01

    The development of a novel non-sulfided catalyst with high activity for the hydrotreatment processing of plant oils, is of high interest as a way to improve the efficient production of renewable diesel. To attempt to develop such a catalyst, we first synthesized a high activity flower-like Ni-PTA catalyst used in the hydrotreatment processes of plant oils. The obtained catalyst was characterized with SEM, EDX, HRTEM, BET, XRD, H2-TPR, XPS and TGA. A probable formation mechanism of flower-like Ni(OH)2 is proposed on the basis of a range of contrasting experiments. The results of GC showed that the conversion yield of Jatropha oil was 98.95%, and the selectivity of C11-C18 alkanes was 70.93% at 360 °C, 3 MPa, and 15 h−1. The activity of this flower-like Ni-PTA catalyst was more than 15 times higher than those of the conventional Ni-PTA/Al2O3 catalysts. Additionally, the flower-like Ni-PTA catalyst exhibited good stability during the process of plant oil hydrotreatment. PMID:26503896

  18. Enhanced cooperativity through design: pendant Co(III)--salen polymer brush catalysts for the hydrolytic kinetic resolution of epichlorohydrin (salen=N,N'-bis(salicylidene)ethylenediamine dianion).

    PubMed

    Gill, Christopher S; Venkatasubbaiah, Krishnan; Phan, Nam T S; Weck, Marcus; Jones, Christopher W

    2008-01-01

    The Co(III)--salen-catalyzed (salen=N,N'-bis(salicylidene)ethylenediamine dianion) hydrolytic kinetic resolution (HKR) of racemic epoxides has emerged as a highly attractive and efficient method of synthesizing chiral C(3) building blocks for intermediates in larger, more complex molecules. HKR reaction rates have displayed a second order dependency on the concentration of active sites, and thus researchers have proposed a bimetallic transition state for the HKR mechanism. Here we report the utilization of pendant Co(III)--salen catalysts on silica supported polymer brushes as a catalyst for the HKR of epichlorohydrin. The novel polymer brush architecture provided a unique framework for promoting site-site interactions as required in the proposed bimetallic transition state of the HKR mechanism. Furthermore, the polymer brushes mimic the environment of soluble polymer-based catalysts, whereas the silica support permitted facile recovery and reuse of the catalyst. The polymer brush catalyst displayed increased activities over the soluble Jacobsen Co--salen catalyst and was observed to retain its high enantioselectivities (>99 %) after each of five reactions despite decreasing activities. Analysis indicated decomposition of the salen ligand as an underlying cause of catalyst deactivation.

  19. A Non-sulfided flower-like Ni-PTA Catalyst that Enhances the Hydrotreatment Efficiency of Plant Oil to Produce Green Diesel

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Chen, Pan; Deng, Lihong; He, Jing; Wang, Luying; Rong, Long; Lei, Jiandu

    2015-10-01

    The development of a novel non-sulfided catalyst with high activity for the hydrotreatment processing of plant oils, is of high interest as a way to improve the efficient production of renewable diesel. To attempt to develop such a catalyst, we first synthesized a high activity flower-like Ni-PTA catalyst used in the hydrotreatment processes of plant oils. The obtained catalyst was characterized with SEM, EDX, HRTEM, BET, XRD, H2-TPR, XPS and TGA. A probable formation mechanism of flower-like Ni(OH)2 is proposed on the basis of a range of contrasting experiments. The results of GC showed that the conversion yield of Jatropha oil was 98.95%, and the selectivity of C11-C18 alkanes was 70.93% at 360 °C, 3 MPa, and 15 h-1. The activity of this flower-like Ni-PTA catalyst was more than 15 times higher than those of the conventional Ni-PTA/Al2O3 catalysts. Additionally, the flower-like Ni-PTA catalyst exhibited good stability during the process of plant oil hydrotreatment.

  20. A Non-sulfided flower-like Ni-PTA Catalyst that Enhances the Hydrotreatment Efficiency of Plant Oil to Produce Green Diesel.

    PubMed

    Liu, Jing; Chen, Pan; Deng, Lihong; He, Jing; Wang, Luying; Rong, Long; Lei, Jiandu

    2015-10-27

    The development of a novel non-sulfided catalyst with high activity for the hydrotreatment processing of plant oils, is of high interest as a way to improve the efficient production of renewable diesel. To attempt to develop such a catalyst, we first synthesized a high activity flower-like Ni-PTA catalyst used in the hydrotreatment processes of plant oils. The obtained catalyst was characterized with SEM, EDX, HRTEM, BET, XRD, H2-TPR, XPS and TGA. A probable formation mechanism of flower-like Ni(OH)2 is proposed on the basis of a range of contrasting experiments. The results of GC showed that the conversion yield of Jatropha oil was 98.95%, and the selectivity of C11-C18 alkanes was 70.93% at 360 °C, 3 MPa, and 15 h(-1). The activity of this flower-like Ni-PTA catalyst was more than 15 times higher than those of the conventional Ni-PTA/Al2O3 catalysts. Additionally, the flower-like Ni-PTA catalyst exhibited good stability during the process of plant oil hydrotreatment.

  1. Highly Durable Supportless Pt Hollow Spheres Designed for Enhanced Oxygen Transport in Cathode Catalyst Layers of Proton Exchange Membrane Fuel Cells.

    PubMed

    Dogan, Didem C; Cho, Seonghun; Hwang, Sun-Mi; Kim, Young-Min; Guim, Hwanuk; Yang, Tae-Hyun; Park, Seok-Hee; Park, Gu-Gon; Yim, Sung-Dae

    2016-10-10

    Supportless Pt catalysts have several advantages over conventional carbon-supported Pt catalysts in that they are not susceptible to carbon corrosion. However, the need for high Pt loadings in membrane electrode assemblies (MEAs) to achieve state-of-the-art fuel cell performance has limited their application in proton exchange membrane fuel cells. Herein, we report a new approach to the design of a supportless Pt catalyst in terms of catalyst layer architecture, which is crucial for fuel cell performance as it affects water management and oxygen transport in the catalyst layers. Large Pt hollow spheres (PtHSs) 100 nm in size were designed and prepared using a carbon template method. Despite their large size, the unique structure of the PtHSs, which are composed of a thin-layered shell of Pt nanoparticles (ca. 7 nm thick), exhibited a high surface area comparable to that of commercial Pt black (PtB). The PtHS structure also exhibited twice the durability of PtB after 2000 potential cycles (0-1.3 V, 50 mV/s). A MEA fabricated with PtHSs showed significant improvement in fuel cell performance compared to PtB-based MEAs at high current densities (>800 mA/cm(2)). This was mainly due to the 2.7 times lower mass transport resistance in the PtHS-based catalyst layers compared to that in PtB, owing to the formation of macropores between the PtHSs and high porosity (90%) in the PtHS catalyst layers. The present study demonstrates a successful example of catalyst design in terms of catalyst layer architecture, which may be applied to a real fuel cell system.

  2. Catalyst-free growth and tailoring morphology of zinc oxide nanostructures by plasma-enhanced deposition at low temperature

    NASA Astrophysics Data System (ADS)

    Chen, W. Z.; Wang, B. B.; Qu, Y. Z.; Huang, X.; Ostrikov, K.; Levchenko, I.; Xu, S.; Cheng, Q. J.

    2017-03-01

    ZnO nanostructures were grown under different deposition conditions from Zn films pre-deposited onto Si substrates in O2-Ar plasma, ignited in an advanced custom-designed plasma-enhanced horizontal tube furnace deposition system. The morphology and structure of the synthesized ZnO nanostructures were systematically and extensively investigated by scanning and transmission electron microscopy, Raman spectroscopy, and atomic force microscopy. It is shown that the morphology of ZnO nanostructures changes from the hybrid ZnO/nanoparticle and nanorod system to the mixture of ZnO nanosheets and nanorods when the growth temperature increases, and the density of ZnO nanorods increases with the increase of oxygen flow rate. The formation of ZnO nanostructures was explained in terms of motion of Zn atoms on the Zn nanoparticle surfaces, and to the local melting of Zn nanoparticles or nanosheets. Moreover, the photoluminescence properties of ZnO nanostructures were studied, and it was revealed that the photoluminescence spectrum features two strong ultraviolet bands at about 378 and 399 nm and a series of weak blue bands within a range of 440-484 nm, related to the emissions of free excitons, near-band edge, and defects of ZnO nanostructures. The obtained results enrich our knowledge on the synthesis of ZnO-based nanostructures and contribute to the development of ZnO-based optoelectronic devices.

  3. Significant enhancement of photoreactivity of graphitic carbon nitride catalysts under acidic conditions and the underlying H(+)-mediated mechanism.

    PubMed

    Zhang, Xue-Song; Tian, Ke; Hu, Jian-Yang; Jiang, Hong

    2015-12-01

    Graphitic carbon nitride (g-C3N4) is an emerging photocatalyst for organic pollutants degradation owing to its excellent stability and metal-free property. In this study, the photocatalytic activity of acidified g-C3N4 (ag-C3N4) was systematically investigated using rhodamine B (rhB) as a model organic pollutant. The results showed the photoreactivity of ag-C3N4 is significantly enhanced with the decrease of pH values. The apparent rate constant (kapp) of rhB degradation over ag-C3N4 is 11.59×10(-3)min(-1) at pH7.0 and it increases to 103.50×10(-3)min(-1) at pH3.0 under visible light. A series of analyses demonstrate that the photodegradation mechanism is a combination of a H(+)-promoted generation of OH and elevation of the redox potential of conduct band of C3N4. The change of surface properties of C3N4 caused by pH variation also affects the degradation of some zwitterionic compounds by changing the adsorption orientation of pollutants. The revealed mechanism of visible light-C3N4-rhB system is meaningful to broaden the usage of C3N4 to the photodegradation of other organic pollutants.

  4. Enhancement of Glycerol Steam Reforming Activity and Thermal Stability by Incorporating CeO2 and TiO2 in Ni- and Co-MCM-41 Catalysts

    NASA Astrophysics Data System (ADS)

    Dade, William N.

    Hydrogen (H2) has many applications in industry with current focus shifted to production of hydrocarbon fuels and valuable oxygenates using the Fischer-Tropsch technology and direct use in proton exchange membrane fuel cell (PEMFC). Hydrogen is generally produced via steam reforming of natural gas or alcohols like methanol and ethanol. Glycerol, a by-product of biodiesel production process, is currently considered to be one of the most attractive sources of sustainable H2 due to its high H/C ratio and bio-based origin. Ni and Co based catalysts have been reported to be active in glycerol steam reforming (GSR); however, deactivation of the catalysts by carbon deposition and sintering under GSR operating conditions is a major challenge. In this study, a series of catalysts containing Ni and Co nanoparticles incorporated in CeO2 and TiO2 modified high surface area MCM-41 have been synthesized using one-pot method. The catalysts are tested for GSR (at H2O/Glycerol mole ratio of 12 and GHSV of 2200 h-1) to study the effect of support modification and reaction temperature (450 - 700 °C) on the product selectivity and long term stability. GSR results revealed that all the catalysts performed significantly well exhibiting over 85% glycerol conversion at 650 °C except Ni catalysts that showed better low temperature activities. Deactivation studies of the catalysts conducted at 650 °C indicated that the Ni-TiO2-MCM-41 and Ni-CeO 2-MCM-41 were resistant to deactivation with ˜100% glycerol conversion for 40 h. In contrast, Co-TiO2-MCM-41 perform poorly as the catalyst rapidly deactivated after 12 h to yield ˜20% glycerol conversion after 40 h. The WAXRD and TGA-DSC analyses of spent catalysts showed a significant amount of coke deposition that might explain catalysts deactivation. The flattening shape of the original BET type IV isotherm with drastic reduction of catalyst surface area can also be responsible for observed drop in catalysts activities.

  5. Catalyst suppliers consolidate further, offer more catalysts

    SciTech Connect

    Rhodes, A.K.

    1995-10-02

    The list of suppliers of catalysts to the petroleum refining industry has decreased by five since Oil and Gas Journal`s survey of refining catalysts and catalytic additives was last published. Despite the consolidation, the list of catalyst designations has grown to about 950 in this latest survey, compared to 820 listed in 1993. The table divides the catalysts by use and gives data on their primary differentiating characteristics, feedstock, products, form, bulk density,catalyst support, active agents, availability, and manufactures.

  6. Hydrocracking catalyst

    SciTech Connect

    Arias, B.; Galiasso, R.; Kum, H.

    1985-02-12

    The invention relates to a particular method for the preparation of a hydrocracking catalyst, using a high iron content bauxite as a basis. This bauxite is ground and screened to a specific size and mixed with three types of additives: a promoter additive of the P, Mo, Co, Ni, W type. A hardener additive of the phosphoric acid type, ammonium phosphate. And a lubricant and pore-generating additive of the polyvinyl alcohol, polyethylene-glycol, starch type. The particularity consists in that the three additives are added simultaneously during the extrusion of the sample. That way, a particular surface composition is obtained which allows for the activity of the catalyst. Extruded products are obtained in sizes of 1/8, 1/16, and 1/32'' and submitted to drying and calcination programs for their activation. The obtained catalyst offers a good mechanical strength, a high content in macropores and a high activity, specifically for the hydrocracking of heavy Venezuelan crudes or residues.

  7. Fabrication of three-dimensional ordered macroporous spinel CoFe2O4 as efficient bifunctional catalysts for the positive electrode of lithium-oxygen batteries.

    PubMed

    Kim, Jong Guk; Noh, Yuseong; Kim, Youngmin; Lee, Seonhwa; Kim, Won Bae

    2017-04-20

    Three-dimensionally ordered macroporous (3DOM) CoFe2O4 (CFO) catalysts were prepared by using the colloidal crystal templating method to be used as bifunctional catalysts of Li-O2 battery positive electrodes. In order to study the relationship between the macropore diameter and charge/discharge behavior, 3DOM CFO catalysts with two different pore diameters of 140 and 60 nm were prepared. The physicochemical properties of the 3DOM CFO catalysts were investigated by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy. When the 3DOM CFO catalyst with a pore diameter of 140 nm (CFO@140) was used in the O2-electrode of Li-O2 batteries, it exhibited a substantially enhanced discharge capacity (ca. 11 658.5 mA h g(-1)) in the first cycle. Moreover, the Li-O2 cells with the CFO@140 catalyst showed cycling stability over 47 cycles at a limited capacity of 500 mA h g(-1) with a reduced potential polarization of 1.13 V, as compared with that with Ketjen Black carbon and the 3DOM CFO of 60 nm pore diameter (CFO@60). Their high cycling stability, low overpotential, high round-trip efficiency, and high rate performance suggest that these 3DOM CFO catalysts could be promising O2-electrode catalysts for next-generation lithium-oxygen batteries.

  8. 77 FR 39452 - Substantial Business Activities; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-03

    ... Internal Revenue Service 26 CFR Part 1 RIN 1545-BK85 Substantial Business Activities; Correction AGENCY..., June 12, 2012 (77 FR 34887) regarding whether a foreign corporation has substantial business activities... Advocacy of the Small Business Administration for comment on their impact on small business.'' LaNita...

  9. Atmospheric-pressure cold plasma for synthesizing Pd/FeO x catalysts with enhanced low-temperature CO oxidation activity

    NASA Astrophysics Data System (ADS)

    Di, Lanbo; Li, Zhuang; Park, Dong-Wha; Lee, Byungjin; Zhang, Xiuling

    2017-06-01

    The FeO x -supported Pd catalyst prepared by co-precipitation has drawn considerable research attention owing to its low-temperature CO oxidation activity. However, Pd utilization should be improved owing to its encapsulation into the support. In this work, atmospheric-pressure cold plasma was employed to synthesize a Pd/FeO x -P catalyst for the first time. The reaction rate of the Pd/FeO x -P catalyst (at 25 °C) is 1.3 times that of the Pd/FeO x -C catalyst prepared by conventional H2 reduction and 3.5 times that in a previous work, owing to the surface enrichment of Pd species, the larger pore diameter of the FeO x support, a higher metallic Pd ratio, and abundant oxygen vacancies.

  10. Catalyst containing oxygen transport membrane

    DOEpatents

    Lane, Jonathan A.; Wilson, Jamie R.; Christie, Gervase Maxwell; Petigny, Nathalie; Sarantopoulos, Christos

    2017-02-07

    A composite oxygen transport membrane having a dense layer, a porous support layer and an intermediate porous layer located between the dense layer and the porous support layer. Both the dense layer and the intermediate porous layer are formed from an ionic conductive material to conduct oxygen ions and an electrically conductive material to conduct electrons. The porous support layer has a high permeability, high porosity, and a microstructure exhibiting substantially uniform pore size distribution as a result of using PMMA pore forming materials or a bi-modal particle size distribution of the porous support layer materials. Catalyst particles selected to promote oxidation of a combustible substance are located in the intermediate porous layer and in the porous support adjacent to the intermediate porous layer. The catalyst particles can be formed by wicking a solution of catalyst precursors through the porous support toward the intermediate porous layer.

  11. Enhanced Hydrodeoxygenation of m -Cresol over Bimetallic Pt–Mo Catalysts through an Oxophilic Metal-Induced Tautomerization Pathway

    SciTech Connect

    Robinson, Allison; Ferguson, Glen Allen; Gallagher, James R.; Cheah, Singfoong; Beckham, Gregg T.; Schaidle, Joshua A.; Hensley, Jesse E.; Medlin, J. Will

    2016-05-26

    Supported bimetallic catalysts consisting of a noble metal (e.g., Pt) and an oxophilic metal (e.g., Mo) have received considerable attention for the hydrodeoxygenation of oxygenated aromatic compounds produced from biomass fast pyrolysis. Here, we report that PtMo can catalyze m-cresol deoxygenation via a pathway involving an initial tautomerization step. In contrast, the dominant mechanism on monometallic Pt/Al2O3 was found to be sequential Pt-catalyzed ring hydrogenation followed by dehydration on the support. Bimetallic Pt10Mo1 and Pt1Mo1 catalysts were found to produce the completely hydrogenated and deoxygenated product, methylcyclohexane (MCH), with much higher yields than monometallic Pt catalysts with comparable metal loadings and surface areas. Over an inert carbon support, MCH formation was found to be slow over monometallic Pt catalysts, while deoxygenation was significant for PtMo catalysts even in the absence of an acidic support material. Experimental studies of m-cresol deoxygenation together with density functional theory calculations indicated that Mo sites on the PtMo bimetallic surface dramatically lower the barrier for m-cresol tautomerization and subsequent deoxygenation. The accessibility of this pathway arises from the increased interaction between the oxygen of m-cresol and the Mo sites in the Pt surface. This interaction significantly alters the configuration of the precursor and transition states for tautomerization. Lastly, a suite of catalyst characterization techniques including X-ray absorption spectroscopy (XAS) and temperature-programmed reduction (TPR) indicate that Mo was present in a reduced state on the bimetallic surface under conditions relevant for reaction. Overall, these results suggest that the use of bifunctional metal catalysts can result in new reaction pathways that are unfavorable on monometallic noble metal catalysts.

  12. Enhanced Hydrodeoxygenation of m -Cresol over Bimetallic Pt–Mo Catalysts through an Oxophilic Metal-Induced Tautomerization Pathway

    SciTech Connect

    Robinson, Allison; Ferguson, Glen Allen; Gallagher, James R.; Cheah, Singfoong; Beckham, Gregg T.; Schaidle, Joshua A.; Hensley, Jesse E.; Medlin, J. Will

    2016-05-26

    Supported bimetallic catalysts consisting of a noble metal (e.g., Pt) and an oxophilic metal (e.g., Mo) have received considerable attention for the hydrodeoxygenation of oxygenated aromatic compounds produced from biomass fast pyrolysis. Here, we report that PtMo can catalyze m-cresol deoxygenation via a pathway involving an initial tautomerization step. In contrast, the dominant mechanism on monometallic Pt/Al2O3 was found to be sequential Pt-catalyzed ring hydrogenation followed by dehydration on the support. Bimetallic Pt10Mo1 and Pt1Mo1 catalysts were found to produce the completely hydrogenated and deoxygenated product, methylcyclohexane (MCH), with much higher yields than monometallic Pt catalysts with comparable metal loadings and surface areas. Over an inert carbon support, MCH formation was found to be slow over monometallic Pt catalysts, while deoxygenation was significant for PtMo catalysts even in the absence of an acidic support material. Experimental studies of m-cresol deoxygenation together with density functional theory calculations indicated that Mo sites on the PtMo bimetallic surface dramatically lower the barrier for m-cresol tautomerization and subsequent deoxygenation. The accessibility of this pathway arises from the increased interaction between the oxygen of m-cresol and the Mo sites in the Pt surface. This interaction significantly alters the configuration of the precursor and transition states for tautomerization. Lastly, a suite of catalyst characterization techniques including X-ray absorption spectroscopy (XAS) and temperature-programmed reduction (TPR) indicate that Mo was present in a reduced state on the bimetallic surface under conditions relevant for reaction. Overall, these results suggest that the use of bifunctional metal catalysts can result in new reaction pathways that are unfavorable on monometallic noble metal catalysts.

  13. Enhancing the cyclability of Li-O2 batteries using PdM alloy nanoparticles anchored on nitrogen-doped reduced graphene as the cathode catalyst

    NASA Astrophysics Data System (ADS)

    Leng, Limin; Li, Jing; Zeng, Xiaoyuan; Song, Huiyu; Shu, Ting; Wang, Haishui; Liao, Shijun

    2017-01-01

    An efficient ORR/OER catalyst was developed by anchoring highly dispersed bimetallic PdM (M = Fe, Co, Ni) alloy nanoparticles on nitrogen-doped reduced graphene oxide (N-rGO). This new type of catalyst exhibited excellent ORR/OER activity, and the addition of transition metals also significantly improved catalytic stability, with the catalyst containing Fe (PdFe/N-rGO) exhibiting the best stability. A battery using this PdFe/N-rGO catalyst was capable of long-term stable cycling for 400 cycles (2000 h) with a limited capacity of 1000 mAh g-1 at 400 mA g-1, which was much longer than a battery with Pd/N-rGO as the catalyst (only 80 cycles, 400 h). We attribute the high performance of these catalysts to the high surface area of N-rGO, the anchoring of highly dispersed Pd alloy nanoparticles, and the prevention of Pd alloy nanoparticle aggregation and dissolution by the presence of the transition metals.

  14. Evident Enhancement of Photoelectrochemical Hydrogen Production by Electroless Deposition of M-B (M = Ni, Co) Catalysts on Silicon Nanowire Arrays.

    PubMed

    Yang, Yong; Wang, Mei; Zhang, Peili; Wang, Weihan; Han, Hongxian; Sun, Licheng

    2016-11-09

    Modification of p-type Si surface by active and stable earth-abundant electrocatalysts is an effective strategy to improve the sluggish kinetics for the hydrogen evolution reaction (HER) at p-Si/electrolyte interface and to develop highly efficient and low-cost photocathodes for hydrogen production from water. To this end, Si nanowire (Si-NW) array has been loaded with highly efficient electrocatalysts, M-B (M = Ni, Co), by facile and quick electroless plating to build M-B catalyst-modified Si nanowire-array-textured photocathodes for water reduction to H2. Compared with the bare Si-NW array, composite Si-NWs/M-B arrays display evidently enhanced photoelectrochemical (PEC) performance. The onset potential (Vphon) of cathodic photocurrent is positively shifted by 530-540 mV to 0.44-0.45 V vs RHE, and the short-circuit current density (Jsc) is up to 19.5 mA cm(-2) in neutral buffer solution under simulated 1 sun illumination. Impressively, the half-cell photopower conversion efficiencies (ηhc) of the optimized Si-NWs/Co-B (2.53%) and Si-NWs/Ni-B (2.45%) are comparable to that of Si-NWs/Pt (2.46%). In terms of the large Jsc, Vphon, and ηhc values, as well as the high Faradaic efficiency, Si-NWs/M-B electrodes are among the top performing Si photocathodes which are modified with HER electrocatalysts but have no buried solid/solid junction.

  15. Catalyst regeneration process including metal contaminants removal

    DOEpatents

    Ganguli, Partha S.

    1984-01-01

    Spent catalysts removed from a catalytic hydrogenation process for hydrocarbon feedstocks, and containing undesired metals contaminants deposits, are regenerated. Following solvent washing to remove process oils, the catalyst is treated either with chemicals which form sulfate or oxysulfate compounds with the metals contaminants, or with acids which remove the metal contaminants, such as 5-50 W % sulfuric acid in aqueous solution and 0-10 W % ammonium ion solutions to substantially remove the metals deposits. The acid treating occurs within the temperature range of 60.degree.-250.degree. F. for 5-120 minutes at substantially atmospheric pressure. Carbon deposits are removed from the treated catalyst by carbon burnoff at 800.degree.-900.degree. F. temperature, using 1-6 V % oxygen in an inert gas mixture, after which the regenerated catalyst can be effectively reused in the catalytic process.

  16. Catalyst and method for aqueous phase reactions

    DOEpatents

    Elliott, Douglas C.; Hart, Todd R.

    1999-01-01

    The present invention is a catalyst in the form of a plurality of porous particles wherein each particle is a support having nickel metal catalytic phase or reduced nickel deposited thereon in a first dispersed phase and an additional metal deposited onto the support in a second dispersed phase. The additional metal is effective in retarding or reducing agglomeration or sintering of the nickel metal catalytic phase without substantially affecting the catalytic activity, thereby increasing the life time of the catalyst.

  17. Enhancing low-temperature activity and durability of Pd-based diesel oxidation catalysts using ZrO2 supports

    SciTech Connect

    Kim, Mi -Young; Kyriakidou, Eleni A.; Choi, Jae -Soon; Toops, Todd J.; Binder, Andrew J.; Thomas, Cyril; Schwartz, Viviane; Chen, Jihua; Hensley, Dale K.; Parks, II, James E.

    2016-01-18

    In this study, we investigated the impact of ZrO2 on the performance of palladium-based oxidation catalysts with respect to low-temperature activity, hydrothermal stability, and sulfur tolerance. Pd supported on ZrO2 and SiO2 were synthesized for a comparative study. Additionally, in an attempt to maximize the ZrO2 surface area and improve sulfur tolerance, a Pd support with ZrO2-dispersed onto SiO2 was studied. The physicochemical properties of the catalysts were examined using ICP, N2 sorption, XRD, SEM, TEM, and NH3-, CO2-, and NOx-TPD. The activity of the Pd catalysts were measured from 60 to 600 °C in a flow of 4000 ppm CO, 500 ppm NO, 1000 ppm C3H6, 4% O2, 5% H2O, and Ar balance. The Pd catalysts were evaluated in fresh, sulfated, and hydrothermally aged states. Overall, the ZrO2-containing catalysts showed considerably higher CO and C3H6 oxidation activity than Pd/SiO2 under the reaction conditions studied.

  18. Tuning the interface of Ni@Ni(OH)2/Pd/rGO catalyst to enhance hydrogen evolution activity and stability

    NASA Astrophysics Data System (ADS)

    Deng, Zihua; Wang, Jun; Nie, Yao; Wei, Zidong

    2017-06-01

    The interface engineering is vital to rational design and synthesis of the heterogeneous catalyst for high-performance electrochemically applications. The smart and elaborate architecture design offers several remarkable advantages, including good dispersion, more exposed active site and good electrical conductivity. We report a trace Pd induced formation of Ni@Ni(OH)2/Pd catalyst on reduced graphene oxides (rGO) by hydrothermal synthesis. We found that the presence of palladium seeds can promote the grain refinement and dispersion of the catalyst. The HRTEM results revealed that most of Ni@Ni(OH)2/Pd with a mean size of ∼10 nm are uniformly dispersed on the rGO sheets, with Pd particles and Ni@Ni(OH)2 balls located side by side. DFT calculations further confirmed a strong interaction existed in the interfaces, which leads to a stable Ni@Ni(OH)2/Pd/rGO morphology. By tailoring Ni@Ni(OH)2-Pd-rGO interfaces of the catalyst, the catalyst gives a current density of 10 mA cm-2 at a small over-potential of 76 mV and exhibits an excellent stability for the hydrogen evolution reaction in an alkaline environments.

  19. Cracking catalyst

    SciTech Connect

    Otterstedt, J. E. A.; Jaras, S. G.; Pudas, R.; Upson, L. L.

    1985-05-07

    A cracking catalyst having good resistance to metal poisoning has at least two particle fractions of different particle sizes, the cracking catalyzing zeolite material being concentrated to the coarser particle size fractions, and the finer particle size fractions being formed from material having relatively lower or no or insignificant cracking catalyzing activity. The particles of the finer particle size fractions have a matrix of kaolin and amorphous alumina--silica and may contain for example, an SO /SUB x/ eliminating additive such as Al/sub 2/O/sub 3/, CaO and/or MgO. The coarser particle size fractions having cracking catalyzing effect have a mean particle size of from 80 to 125 ..mu..m and the finer particle size fractions a mean particle size of from 30 to 75 ..mu..m. The coarser particle size fractions have a zeolite content of at least 20 weight % and may have a zeolite content of up to 100 weight %, the remainder consisting essentially of material which has relatively lower or no or insignificant cracking-catalyzing activity and which consists of kaolin and amorphous alumina-silica. The catalyst mass as a whole may have a zeolite content of up to 50 weight %.

  20. Nanostructured catalysts for organic transformations.

    PubMed

    Chng, Leng Leng; Erathodiyil, Nandanan; Ying, Jackie Y

    2013-08-20

    The development of green, sustainable and economical chemical processes is one of the major challenges in chemistry. Besides the traditional need for efficient and selective catalytic reactions that will transform raw materials into valuable chemicals, pharmaceuticals and fuels, green chemistry also strives for waste reduction, atomic efficiency and high rates of catalyst recovery. Nanostructured materials are attractive candidates as heterogeneous catalysts for various organic transformations, especially because they meet the goals of green chemistry. Researchers have made significant advances in the synthesis of well-defined nanostructured materials in recent years. Among these are novel approaches that have permitted the rational design and synthesis of highly active and selective nanostructured catalysts by controlling the structure and composition of the active nanoparticles (NPs) and by manipulating the interaction between the catalytically active NP species and their support. The ease of isolation and separation of the heterogeneous catalysts from the desired organic product and the recovery and reuse of these NPs further enhance their attractiveness as green and sustainable catalysts. This Account reviews recent advances in the use of nanostructured materials for catalytic organic transformations. We present a broad overview of nanostructured catalysts used in different types of organic transformations including chemoselective oxidations and reductions, asymmetric hydrogenations, coupling reactions, C-H activations, oxidative aminations, domino and tandem reactions, and more. We focus on recent research efforts towards the development of the following nanostructured materials: (i) nanostructured catalysts with controlled morphologies, (ii) magnetic nanocomposites, (iii) semiconductor-metal nanocomposites, and (iv) hybrid nanostructured catalysts. Selected examples showcase principles of nanoparticle design such as the enhancement of reactivity, selectivity

  1. Water-Enhanced Synthesis of Higher Alcohols from CO2 Hydrogenation over a Pt/Co3O4 Catalyst under Milder Conditions.

    PubMed

    He, Zhenhong; Qian, Qingli; Ma, Jun; Meng, Qinglei; Zhou, Huacong; Song, Jinliang; Liu, Zhimin; Han, Buxing

    2016-01-11

    The effect of water on CO2 hydrogenation to produce higher alcohols (C2-C4) was studied. Pt/Co3O4, which had not been used previously for this reaction, was applied as the heterogeneous catalyst. It was found that water and the catalyst had an excellent synergistic effect for promoting the reaction. High selectivity of C2-C4 alcohols could be achieved at 140 °C (especially with DMI (1,3-dimethyl-2-imidazolidinone) as co-solvent), which is a much lower temperature than reported previously. The catalyst could be reused at least five times without reducing the activity and selectivity. D2O and (13)CH3OH labeling experiments indicated that water involved in the reaction and promoted the reaction kinetically, and ethanol was formed via CH3OH as an intermediate.

  2. Oil removal of spent hydrotreating catalyst CoMo/Al2O3 via a facile method with enhanced metal recovery.

    PubMed

    Yang, Yue; Xu, Shengming; Li, Zhen; Wang, Jianlong; Zhao, Zhongwei; Xu, Zhenghe

    2016-11-15

    Deoiling process is a key issue for recovering metal values from spent hydrotreating catalysts. The oils can be removed with organic solvents, but the industrialized application of this method is greatly hampered by the high cost and complex processes. Despite the roasting method is simple and low-cost, it generates hardest-to-recycle impurities (CoMoO4 or NiMoO4) and enormous toxic gases. In this study, a novel and facile approach to remove oils from the spent hydrotreating catalysts is developed. Firstly, surface properties of spent catalysts are characterized to reveal the possibility of oil removal. And then, oils are removed with water solution under the conditions of 90°C, 0.1wt% SDS, 2.0wt% NaOH and 10ml/gL/S ratio for 4h. Finally, thermal treatment and leaching tests are carried out to further explore the advantages of oil removal. The results show that no hardest-to-recycle impurity CoMoO4 is found in XPS spectra of thermally treated samples after deoiling and molybdenum is leached completely with sodium carbonate solution. It means that the proposed deoiling method can not only remove oils simply and without enormous harmful gases generating, but also avoid the generation of detrimental impurity and promote recycling of valuable metals from spent hydrotreating catalysts. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. The enhancement of the hydrolysis of bamboo biomass in ionic liquid with chitosan-based solid acid catalysts immobilized with metal ions.

    PubMed

    Cheng, Jie; Wang, Nan; Zhao, Dezhou; Qin, Dandan; Si, Wenqing; Tan, Yunfei; Wei, Shun'an; Wang, Dan

    2016-11-01

    Three kinds of sulfonated cross-linked chitosan (SCCR) immobilized with metal ions of Cu(2+), Fe(3+) and Zn(2+) individually were synthesized and firstly used as solid acid catalysts in the hydrolysis of bamboo biomass. FTIR spectra showed that metal ions had been introduced into SCCR and the N-metal ions coordinate bound was formed. The particle sizes of these catalysts were about 500-1000μm with a pore size of 50-160μm. All of the three kinds of catalysts performed well for bamboo hydrolysis with 1-butyl-3-methyl-imidazolium chloride used as solvent. The most effective one was sulfonated cross-linked chitosan immobilized with Fe(3+) (Fe(3+)-SCCR). TRS yields were up to 73.42% for hydrolysis of bamboo powder in [C4mim]Cl with Fe(3+)-SCCR at 120°C and 20RPM after 24h. These novel chitosan-based metal ions immobilized solid acid catalysts with ionic liquids as the solvent might be promising to facilitate cost-efficient conversion of biomass into biofuels and bioproducts. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. 21 CFR 514.4 - Substantial evidence.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS NEW ANIMAL DRUG APPLICATIONS General Provisions § 514.4 Substantial evidence... adequate and well-controlled studies, such as a study in a target species, study in laboratory...

  5. Toward More Substantial Theories of Language Acquisition

    ERIC Educational Resources Information Center

    Jenson, Cinnamon Ann

    2015-01-01

    Cognitive linguists argue that certain sets of knowledge of language are innate. However, critics have argued that the theoretical concept of "innateness" should be eliminated since it is ambiguous and insubstantial. In response, I aim to strengthen theories of language acquisition and identify ways to make them more substantial. I…

  6. Toward More Substantial Theories of Language Acquisition

    ERIC Educational Resources Information Center

    Jenson, Cinnamon Ann

    2015-01-01

    Cognitive linguists argue that certain sets of knowledge of language are innate. However, critics have argued that the theoretical concept of "innateness" should be eliminated since it is ambiguous and insubstantial. In response, I aim to strengthen theories of language acquisition and identify ways to make them more substantial. I…

  7. Substantially Oxygen-Free Contact Tube

    NASA Technical Reports Server (NTRS)

    Pike, James F. (Inventor)

    1991-01-01

    A device for arc welding is provided in which a continuously-fed electrode wire is in electrical contact with a contact tube. The contact tube is improved by using a substantially oxygen-free conductive alloy in order to reduce the amount of electrical erosion.

  8. Substantially oxygen-free contact tube

    NASA Technical Reports Server (NTRS)

    Pike, James F. (Inventor)

    1993-01-01

    A device for arc welding is provided in which a continuously-fed electrode wire is in electrical contact with a contact tube. The contact tube is improved by using a substantially oxygen-free conductive alloy in order to reduce the amount of electrical erosion.

  9. Low-Temperature CO-Oxidation Catalysts for Long-Life CO2 Lasers

    NASA Technical Reports Server (NTRS)

    Schryer, David R. (Editor); Hoflund, Gar B. (Editor)

    1990-01-01

    Low-temperature CO-oxidation catalysts are necessary for closed-cycle pulsed CO2 lasers as well as for other applications, including air purification. The papers presented in this volume discuss several such catalysts, including information on catalyst preparation, techniques for enhancing catalyst performance, laboratory and laser test results, and mechanistic considerations.

  10. Electrochemical catalyst recovery method

    DOEpatents

    Silva, Laura J.; Bray, Lane A.

    1995-01-01

    A method of recovering catalyst material from latent catalyst material solids includes: a) combining latent catalyst material solids with a liquid acid anolyte solution and a redox material which is soluble in the acid anolyte solution to form a mixture; b) electrochemically oxidizing the redox material within the mixture into a dissolved oxidant, the oxidant having a potential for oxidation which is effectively higher than that of the latent catalyst material; c) reacting the oxidant with the latent catalyst material to oxidize the latent catalyst material into at least one oxidized catalyst species which is soluble within the mixture and to reduce the oxidant back into dissolved redox material; and d) recovering catalyst material from the oxidized catalyst species of the mixture. The invention is expected to be particularly useful in recovering spent catalyst material from petroleum hydroprocessing reaction waste products having adhered sulfides, carbon, hydrocarbons, and undesired metals, and as well as in other industrial applications.

  11. Electrochemical catalyst recovery method

    DOEpatents

    Silva, L.J.; Bray, L.A.

    1995-05-30

    A method of recovering catalyst material from latent catalyst material solids includes: (a) combining latent catalyst material solids with a liquid acid anolyte solution and a redox material which is soluble in the acid anolyte solution to form a mixture; (b) electrochemically oxidizing the redox material within the mixture into a dissolved oxidant, the oxidant having a potential for oxidation which is effectively higher than that of the latent catalyst material; (c) reacting the oxidant with the latent catalyst material to oxidize the latent catalyst material into at least one oxidized catalyst species which is soluble within the mixture and to reduce the oxidant back into dissolved redox material; and (d) recovering catalyst material from the oxidized catalyst species of the mixture. The invention is expected to be particularly useful in recovering spent catalyst material from petroleum hydroprocessing reaction waste products having adhered sulfides, carbon, hydrocarbons, and undesired metals, and as well as in other industrial applications. 3 figs.

  12. Monolithic catalyst catalytic converter with catalyst holding expansible retainer ring

    SciTech Connect

    Isogai, K.; Koga, I.; Ohmori, N.; Okamoto, M.; Takeuchi, M.; Takita, N.; Tobi, N.

    1984-05-15

    A catalytic converter includes a tubular casing within which is held a monolithic catalyst body which is generally of a columnar shape. The ends of the monolithic catalyst body are each engaged with a cushion ring, and each cushion ring is engaged with a retainer ring therefor, which is substantially axially fixed within the casing near to an end thereof. The monolithic catalyst body is supported within the casing by axial compressive force present between the retainer rings on the outside, the cushion rings between the retainer rings, and the monolithic catalyst body between the cushion rings. At least one of the retainer rings is formed with a break in a part of its circumference, the two free ends of the retainer ring on the two sides of the break being movable with distortion of the retainer ring through a certain distance, according to changes of temperature of the retainer ring, with respect to one another in the mutual relative direction which causes the overall circumference of the retainer ring to be diminished, so that expansion of the retainer ring when it heats up is adsorbed, and the retainer ring is not subject to kinking or folding when the catalytic converter operates in the hot condition.

  13. Zeolites for reforming catalysts

    SciTech Connect

    Kao, J.L.; Nadler, M.; Potter, M.J.; Martir, R.V.

    1991-01-22

    This patent describes a reforming catalyst exhibiting enhanced selectivity, activity, and activity maintenance. It comprises: zeolite crystals having a pH within the range of 9.4 to 10.0, wherein the pH is determined by measuring pH of supernatent liquid from a mixture of one part of the zeolite crystals with ten parts of dionized water by weight, and comprising exchangeable cations and at least one catalytically active metal selected from the group consisting of Group VII of the Periodic Table of Elements, tin and germanium. This patten also describes a process for treating zeolite to have a pH within a range effective in imparting enhanced activity, selectivity and activity maintenance to catalysts loaded onto the zeolite. The process comprising washing zeolite with an aqueous liquid in a manner so as to result with zeolite having a pH within the pH range of 9.4 to 10.0. The PH of supernatent liquid from a mixture of one part of the zeolite crystals with ten parts of dionized water by weight.

  14. Boosting performance of low temperature fuel cell catalysts by subtle ionic liquid modification.

    PubMed

    Zhang, Gui-Rong; Munoz, Macarena; Etzold, Bastian J M

    2015-02-18

    High cost and poor stability of the oxygen reduction reaction (ORR) electrocatalysts are the major barriers for broad-based application of polymer electrolyte membrane fuel cells. Here we report a facile and scalable approach to improve Pt/C catalysts for ORR, by modification with small amounts of hydrophobic ionic liquid (IL). The ORR performance of these IL-modified catalysts can be readily manipulated by varying the degree of IL filling, leading to a 3.4 times increase in activity. Besides, the IL-modified catalysts exhibit substantially enhanced stability relative to Pt/C. The enhanced performance is attributed to the optimized microenvironment at the interface of Pt and electrolyte, where advantages stemming from an increased number of free sites, higher oxygen concentration in the IL and electrostatic stabilization of the nanoparticles develop fully, at the same time that the drawback of mass transfer limitation remains suppressed. These findings open a new avenue for catalyst optimization for next-generation fuel cells.

  15. Pretreatment of CO oxidation catalysts

    NASA Technical Reports Server (NTRS)

    Vannorman, John D.

    1988-01-01

    CO oxidation catalysts with high activity in the range of 25 C to 100 C are important for long-life, closed-cycle operation of pulsed carbon dioxide 2 lasers. A reductive pretreatment with either CO or H sub 2 was shown to significantly enhance the activity of a commerically-available platinum on tin (IV) oxide (Pt/SnO2) catalyst relative to an oxidative or inert pretreatment or no pretreatment. Pretreatment at temperatures of 175 C and above caused an initial dip in observed CO or O sub 2 loss or CO sub 2 formation in a test gas mixture of 1 percent CO and 0.5 percent O sub 2 in a He gas matrix before a steady-state yield was obtained. This dip was found to be caused by dehydration of the surface of the catalyst and was readily eliminated by humidifying the catalyst or the test gas mixture. It was also found that too much moisture resulted in a lower overall yield of CO sub 2. Under similar conditions, it is hypothesized that the effect of the humidification is to increase the concentration of OH groups on the surface of the catalyst. The effect of having high concentration of CO sub 2 in the test gas mixture upon the loss of CO and O sub 2 as well as the effect of periods of relaxation of the catalyst under non-test gas conditions was studied. The purpose of these studies was to gain an insight into the mechanism of CO oxidation on this type of catalyst.

  16. Long-Life Catalyst

    NASA Technical Reports Server (NTRS)

    1999-01-01

    STC Catalysts, Inc. (SCi) manufactures a noble metal reducible oxide catalyst consisting primarily of platinum and tin dioxide deposited on a ceramic substrate. It is an ambient temperature oxidation catalyst that was developed primarily for Carbon Dioxide Lasers.The catalyst was developed by the NASA Langley Research Center for the Laser Atmospheric Wind Sounder Program (LAWS) which was intended to measure wind velocity on a global basis. There are a number of NASA owned patents covering various aspects of the catalyst.

  17. New catalyst permits desulfurization of heavier resids. [RCD-8 catalyst, RCD Unibon process

    SciTech Connect

    Olson, R.K.; Russ, M.B.

    1981-01-01

    (1) The commerically proven RCD-8 catalyst offers superior metal removal and a twofold improvement in metal tolerance. For existing reduced-crude desulfurization units, this catalyst will allow processing feedstocks containing much higher metals level without sacrificing run length. Utilization of RCD-8 for new unit designs will significantly reduce investments for reactors and catalysts. RCD-8 has also proven to be an excellent catalyst for the desulfurization of heavy vacuum bottoms. Sulfur removal is accompanied by significant reduction in asphaltenes, non-distillables, and Conradson carbon. Thus, RCD-8 represents a substantial improvement over other hydroprocessing catalysts used in preparing feed for FCC, coking, hydrocracking or solvent-extraction units, in addition to producing low-sulfur fuel oil. 1 ref.

  18. Two-catalyst hydrocracking process

    SciTech Connect

    Bertolacini, R.; Yu, A.

    1980-07-08

    A process is described for the hydrocracking of a hydrocarbon stream boiling above a temperature of about 300/sup 0/F (149/sup 0/C) and containing a substantial amount of organic nitrogen-containing compounds, which process comprises: contacting said stream in a frist reaction zone under hydrocracking conditions and in the presence of hydrogen with a first catalyst comprising a hydrogenation component comprising nickel and molybdenum or nickel and tungsten and a co-catalytic acidic cracking support comprising an ultrastable, large-pore crystalline aluminosilicate material suspended in and distributed throughout a matrix of silica-alumina to provide a first hydrocracked effluent, said hydrogenation component of said first catalyst being present in the elemtnal form, as oxides, as sulfides, or mixtures thereof; contacting said first hydrocracked effluent in a second reaction zone under hydrocracking conditions and in the presence of hydrogen with a second catalyst comprising a hydrogenation component comprising cobalt and molybdenum and a co-catalytic acidic cracking support comprising an ultrastable, large-pore crystalline aluminosilicate material suspended in and distributed throughout a matrix of silica-alumina to provide a second hydrocracked effluent,said hydrogenation component of said second catalyst being present in the elemental form, as oxides, as sulfides, or mixtures thereof; and recovering useful products from said second hydrocracked effluent.

  19. Dearomatization of jet fuel on irradiated platinum-supported catalyst

    NASA Astrophysics Data System (ADS)

    Múčka, V.; Ostrihoňová, A.; Kopernický, I.; Mikula, O.

    The effect of ionizing radiation ( 60Co γ-rays) on Pt-supported catalyst used for the dearomatization of jet fuel with distillation in the range 395-534 K has been studied. Pre-irradiation of the catalyst with doses in the range 10 2-5 × 10 4 Gy leads to the partial catalyst activation. Irradiation of the catalyst enhances its resistance to catalyst poisons, particularly to sulphur-compounds, and this is probably the reason for its catalytic activity being ˜60-100% greater than that of un-irradiated catalyst. Optimum conditions for dearomatization on the irradiated catalyst were found and, by means of a rotary three-factorial experiment, it was shown that these lie at lower temperatures and lower pressures than those for un-irradiated catalyst.

  20. Final Report of a CRADA Between Pacific Northwest National Laboratory and Cummins, Incorporated (CRADA No.PNNL/283): “Enhanced High and Low Temperature Performance of NOx Reduction Catalyst Materials”

    SciTech Connect

    Gao, Feng; Szanyi, Janos; Wang, Yilin; Wang, Yong; Peden, Charles HF; Howden, Ken; Currier, Neal; Kamasamudram, Krishna; Kumar, Ashok; Li, J.; Stafford, R. J.; Yezerets, Aleksey; Luo, J.; Chen, H. Y.

    2016-09-01

    of the most daunting challenges in R&D on new catalyst materials and processes that can effectively eliminate emissions at these quite low exhaust temperatures. This project has two clear focuses: (1) development of potassium-based high-temperature NSR materials, and studying their key causes of deactivation and methods of regeneration. By comparing results obtained on ‘Simple Model’ Pt-K/Al2O3 with ‘Enhanced Model’ Pt-K/ MgAlOx and Pt-K/TiO2 materials, we have developed an understanding of the role of various additives on the deactivation and regeneration processes. Studies have also been performed on the real commercial samples being used in a Dodge Ram truck with a Cummins diesel emission control system. However, the results about these ‘commercial samples’ will not be covered in this report. Following a brief description of our experimental approach, we will present a few highlights from some of the work performed in this CRADA with more details about these results provided in publications/reports/presentations lists presented at the end of the report. (2) for the Cu and Fe/Chabazite SCR catalysts, since these are so newly developed and references from open literature and industry are nearly absent, our work started from zeolite synthesis and catalyst synthesis methodology development, before research on their low- and high-temperature performance, deactivation, regeneration, etc. was conducted. Again, most work reported here is based on our “model” catalysts synthesized in-house. Work done on the ‘commercial samples’ will not be covered in this report.

  1. Metallic State FeS Anchored (Fe)/Fe3O4/N-Doped Graphitic Carbon with Porous Spongelike Structure as Durable Catalysts for Enhancing Bioelectricity Generation.

    PubMed

    Xu, Xin; Dai, Ying; Yu, Jia; Hao, Liang; Duan, Yaqiang; Sun, Ye; Zhang, Yanhong; Lin, Yuhui; Zou, Jinlong

    2017-03-29

    The critical issues in practical application of microbial fuel cells (MFCs) for wastewater treatment are the high cost and poor activity and durability of precious metal catalysts. To alleviate the activity loss and kinetic barriers for oxygen reduction reaction (ORR) on cathode, (Fe)/Fe3O4/FeS/N-doped graphitic carbon ((Fe)/Fe3O4/FeS/NGC) is prepared as ORR catalyst through a one-step method using waste pomelo skins as carbon source. Various characterization techniques and electrochemical analyses are conducted to illustrate the correlation between structural characteristics and catalytic activity. MFCs with Fe/Fe3O4/FeS/NGC (900 °C) cathode produces the maximum power density of 930 ± 10 mW m(-2) (Pt/C of 489 mW m(-2)) and maintains a good long-term durability, which only declines 18% after 90 day operation. Coulombic efficiency (22.2%) obtained by Fe/Fe3O4/FeS/NGC (900 °C) cathode is significantly higher than that of Pt/C (17.3%). Metallic state FeS anchored in porous NGC skeleton can boost electron transport through the interconnected channels in spongelike structure to improve catalytic activity. Charge delocalization of C atoms can be strengthened by N atoms incorporation into carbon skeleton, which correspondingly contributes to the O2 chemisorptions and O-O bond weakening during ORR. Energetically existed active components (Fe and N species) are more efficient than Pt to trap and consume electrons in catalyzing ORR in wastewater containing Pt-poisoning substances (bacterial metabolites). (Fe)/Fe3O4/FeS/NGC catalysts with the advantages of durable power outputs and environmental-friendly raw material can cover the shortages of Pt/C and provide an outlook for further applications of these catalysts.

  2. Enhanced catalytic toluene oxidation by interaction between copper oxide and manganese oxide in Cu-O-Mn/γ-Al2O3 catalysts

    NASA Astrophysics Data System (ADS)

    Wang, Hongpei; Lu, Yiyuan; Han, YuXiang; Lu, Chunliang; Wan, Haiqin; Xu, Zhaoyi; Zheng, Shourong

    2017-10-01

    Toward catalytic oxidation of toluene, Cu-O-Mn/γ-Al2O3 catalysts with series molar ratios of Cu/Mn were prepared using an impregnation method. The surface structure and chemical state of the as-prepared catalysts were characterized by the combination of X-ray diffraction (XRD), N2 adsorption/desorption, UV-vis spectroscopy (UV-vis), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and H2 temperature programmed reduction (H2-TPR). The results demonstrated that copper oxide and manganese oxide were highly dispersed on the γ-Al2O3 support. Meanwhile, there is an interaction between copper oxide and manganese oxide, depending on the atomic ratio of Cu/Mn. At the ratio of Cu/Mn = 1:1.5, the interaction between Cu and Mn oxides reached the strongest, thus leading to the highest catalytic activity and turn over frequency among all of the ratios. The temperature for complete combustion of toluene over the strongest interaction sample could be 350 °C, which could further decrease to 300 °C when tuning the loading amount of Cu and Mn. Findings in this work are important for the design of efficient catalyst by tuning the interaction between each components.

  3. Ti3C2 MXene co-catalyst on metal sulfide photo-absorbers for enhanced visible-light photocatalytic hydrogen production

    PubMed Central

    Ran, Jingrun; Gao, Guoping; Li, Fa-Tang; Ma, Tian-Yi; Du, Aijun; Qiao, Shi-Zhang

    2017-01-01

    Scalable and sustainable solar hydrogen production through photocatalytic water splitting requires highly active and stable earth-abundant co-catalysts to replace expensive and rare platinum. Here we employ density functional theory calculations to direct atomic-level exploration, design and fabrication of a MXene material, Ti3C2 nanoparticles, as a highly efficient co-catalyst. Ti3C2 nanoparticles are rationally integrated with cadmium sulfide via a hydrothermal strategy to induce a super high visible-light photocatalytic hydrogen production activity of 14,342 μmol h−1 g−1 and an apparent quantum efficiency of 40.1% at 420 nm. This high performance arises from the favourable Fermi level position, electrical conductivity and hydrogen evolution capacity of Ti3C2 nanoparticles. Furthermore, Ti3C2 nanoparticles also serve as an efficient co-catalyst on ZnS or ZnxCd1−xS. This work demonstrates the potential of earth-abundant MXene family materials to construct numerous high performance and low-cost photocatalysts/photoelectrodes. PMID:28045015

  4. Ti3C2 MXene co-catalyst on metal sulfide photo-absorbers for enhanced visible-light photocatalytic hydrogen production

    NASA Astrophysics Data System (ADS)

    Ran, Jingrun; Gao, Guoping; Li, Fa-Tang; Ma, Tian-Yi; Du, Aijun; Qiao, Shi-Zhang

    2017-01-01

    Scalable and sustainable solar hydrogen production through photocatalytic water splitting requires highly active and stable earth-abundant co-catalysts to replace expensive and rare platinum. Here we employ density functional theory calculations to direct atomic-level exploration, design and fabrication of a MXene material, Ti3C2 nanoparticles, as a highly efficient co-catalyst. Ti3C2 nanoparticles are rationally integrated with cadmium sulfide via a hydrothermal strategy to induce a super high visible-light photocatalytic hydrogen production activity of 14,342 μmol h-1 g-1 and an apparent quantum efficiency of 40.1% at 420 nm. This high performance arises from the favourable Fermi level position, electrical conductivity and hydrogen evolution capacity of Ti3C2 nanoparticles. Furthermore, Ti3C2 nanoparticles also serve as an efficient co-catalyst on ZnS or ZnxCd1-xS. This work demonstrates the potential of earth-abundant MXene family materials to construct numerous high performance and low-cost photocatalysts/photoelectrodes.

  5. Ti3C2 MXene co-catalyst on metal sulfide photo-absorbers for enhanced visible-light photocatalytic hydrogen production.

    PubMed

    Ran, Jingrun; Gao, Guoping; Li, Fa-Tang; Ma, Tian-Yi; Du, Aijun; Qiao, Shi-Zhang

    2017-01-03

    Scalable and sustainable solar hydrogen production through photocatalytic water splitting requires highly active and stable earth-abundant co-catalysts to replace expensive and rare platinum. Here we employ density functional theory calculations to direct atomic-level exploration, design and fabrication of a MXene material, Ti3C2 nanoparticles, as a highly efficient co-catalyst. Ti3C2 nanoparticles are rationally integrated with cadmium sulfide via a hydrothermal strategy to induce a super high visible-light photocatalytic hydrogen production activity of 14,342 μmol h(-1 )g(-1) and an apparent quantum efficiency of 40.1% at 420 nm. This high performance arises from the favourable Fermi level position, electrical conductivity and hydrogen evolution capacity of Ti3C2 nanoparticles. Furthermore, Ti3C2 nanoparticles also serve as an efficient co-catalyst on ZnS or ZnxCd1-xS. This work demonstrates the potential of earth-abundant MXene family materials to construct numerous high performance and low-cost photocatalysts/photoelectrodes.

  6. Tin oxide dependence of the CO2 reduction efficiency on tin electrodes and enhanced activity for tin/tin oxide thin-film catalysts.

    PubMed

    Chen, Yihong; Kanan, Matthew W

    2012-02-01

    The importance of tin oxide (SnO(x)) to the efficiency of CO(2) reduction on Sn was evaluated by comparing the activity of Sn electrodes that had been subjected to different pre-electrolysis treatments. In aqueous NaHCO(3) solution saturated with CO(2), a Sn electrode with a native SnO(x) layer exhibited potential-dependent CO(2) reduction activity consistent with previously reported activity. In contrast, an electrode etched to expose fresh Sn(0) surface exhibited higher overall current densities but almost exclusive H(2) evolution over the entire 0.5 V range of potentials examined. Subsequently, a thin-film catalyst was prepared by simultaneous electrodeposition of Sn(0) and SnO(x) on a Ti electrode. This catalyst exhibited up to 8-fold higher partial current density and 4-fold higher faradaic efficiency for CO(2) reduction than a Sn electrode with a native SnO(x) layer. Our results implicate the participation of SnO(x) in the CO(2) reduction pathway on Sn electrodes and suggest that metal/metal oxide composite materials are promising catalysts for sustainable fuel synthesis.

  7. Does Pluto have a substantial atmosphere

    SciTech Connect

    Trafton, L.

    1980-01-01

    The presence of CH4 ice on Pluto implies that Pluto may have a substantial atmosphere consisting of heavy gases. Without such an atmosphere, sublimation of the CH4 ice would be so rapid on a cosmogonic time scale that either such an atmosphere would soon develop through the exposure of gases trapped in the CH4 ice or else the surface CH4 ice would soon be all sublimated away as other, more stable, ices became exposed. If such stable ices were present from the beginning, the existence of CH4 frosts would also imply that Pluto's present atmosphere contains a remnant of its primordial atmosphere.

  8. Hydrocarbon reforming catalyst material and configuration of the same

    DOEpatents

    Singh, Prabhakar; Shockling, Larry A.; George, Raymond A.; Basel, Richard A.

    1996-01-01

    A hydrocarbon reforming catalyst material comprising a catalyst support impregnated with catalyst is provided for reforming hydrocarbon fuel gases in an electrochemical generator. Elongated electrochemical cells convert the fuel to electrical power in the presence of an oxidant, after which the spent fuel is recirculated and combined with a fresh hydrocarbon feed fuel forming the reformable gas mixture which is fed to a reforming chamber containing a reforming catalyst material, where the reforming catalyst material includes discrete passageways integrally formed along the length of the catalyst support in the direction of reformable gas flow. The spent fuel and/or combusted exhaust gases discharged from the generator chamber transfer heat to the catalyst support, which in turn transfers heat to the reformable gas and to the catalyst, preferably via a number of discrete passageways disposed adjacent one another in the reforming catalyst support. The passageways can be slots extending inwardly from an outer surface of the support body, which slots are partly defined by an exterior confining wall. According to a preferred embodiment, the catalyst support is non-rigid, porous, fibrous alumina, wherein the fibers are substantially unsintered and compressible, and the reforming catalyst support is impregnated, at least in the discrete passageways with Ni and MgO, and has a number of internal slot passageways for reformable gas, the slot passageways being partly closed by a containing outer wall.

  9. Hydrocarbon reforming catalyst material and configuration of the same

    DOEpatents

    Singh, P.; Shockling, L.A.; George, R.A.; Basel, R.A.

    1996-06-18

    A hydrocarbon reforming catalyst material comprising a catalyst support impregnated with catalyst is provided for reforming hydrocarbon fuel gases in an electrochemical generator. Elongated electrochemical cells convert the fuel to electrical power in the presence of an oxidant, after which the spent fuel is recirculated and combined with a fresh hydrocarbon feed fuel forming the reformable gas mixture which is fed to a reforming chamber containing a reforming catalyst material, where the reforming catalyst material includes discrete passageways integrally formed along the length of the catalyst support in the direction of reformable gas flow. The spent fuel and/or combusted exhaust gases discharged from the generator chamber transfer heat to the catalyst support, which in turn transfers heat to the reformable gas and to the catalyst, preferably via a number of discrete passageways disposed adjacent one another in the reforming catalyst support. The passageways can be slots extending inwardly from an outer surface of the support body, which slots are partly defined by an exterior confining wall. According to a preferred embodiment, the catalyst support is non-rigid, porous, fibrous alumina, wherein the fibers are substantially unsintered and compressible, and the reforming catalyst support is impregnated, at least in the discrete passageways with Ni and MgO, and has a number of internal slot passageways for reformable gas, the slot passageways being partly closed by a containing outer wall. 5 figs.

  10. Integrated current collector and catalyst support

    DOEpatents

    Bregoli, Lawrence J.

    1985-10-22

    An integrated current collecting electrode for a molten carbonate fuel cell includes a corrugated metal conductive strip positioned in contact with a catalyst layer. The corrugations of the metal strip form a plurality of gas channels immediately adjacent the surface of the catalyst through which a reactant gas flows. Each channel is filled with a particulate material to maintain separation between the metal strip and the catalyst in ensuring gas channel integrity. The catalyst may be in the form of a compacted, particulate material provided the particle size of the material within the gas channels is larger than that of the catalyst particles to prevent catalyst migration to the metal conductor and provide reactant gas access to the catalyst layer. The gas channels formed by the corrugations of the metal strip are arranged in an offset pattern along the direction of gas flow for improved reactant gas distribution to the catalyst layer. The particulate material positioned within the gas flow channels may be a ceramic conductor such as a perovskite or a spinel for enhanced current collection.

  11. Integrated current collector and catalyst support

    DOEpatents

    Bregoli, L.J.

    1984-10-17

    An integrated current collecting electrode for a molten carbonate fuel cell includes a corrugated metal conductive strip positioned in contact with a catalyst layer. The corrugations of the metal strip form a plurality of gas channels immediately adjacent the surface of the catalyst through which a reactant gas flows. Each channel is filled with a particulate material to maintain separation between the metal strip and the catalyst in ensuring gas channel integrity. The catalyst may be in the form of a compacted, particulate material provided the particle size of the material within the gas channels is larger than that of the catalyst particles to prevent catalyst migration to the metal conductor and provide reactant gas access to the catalyst layer. The gas channels formed by the corrugations of the metal strip are arranged in an offset pattern along the direction of gas flow for improved reactant gas distribution to the catalyst layer. The particulate material positioned within the gas flow channels may be a ceramic conductor such as a perovskite or a spinel for enhanced current collection.

  12. Prelife catalysts and replicators

    PubMed Central

    Ohtsuki, Hisashi; Nowak, Martin A.

    2009-01-01

    Life is based on replication and evolution. But replication cannot be taken for granted. We must ask what there was prior to replication and evolution. How does evolution begin? We have proposed prelife as a generative system that produces information and diversity in the absence of replication. We model prelife as a binary soup of active monomers that form random polymers. ‘Prevolutionary’ dynamics can have mutation and selection prior to replication. Some sequences might have catalytic activity, thereby enhancing the rates of certain prelife reactions. We study the selection criteria for these prelife catalysts. Their catalytic efficiency must be above certain critical values. We find a maintenance threshold and an initiation threshold. The former is a linear function of sequence length, and the latter is an exponential function of sequence length. Therefore, it is extremely hard to select for prelife catalysts that have long sequences. We compare prelife catalysis with a simple model for replication. Assuming fast template-based elongation reactions, we can show that replicators have selection thresholds that are independent of their sequence length. Our calculation demonstrates the efficiency of replication and provides an explanation of why replication was selected over other forms of prelife catalysis. PMID:19692408

  13. Substantiating powder metal life methodologies for engines

    NASA Astrophysics Data System (ADS)

    Domas, P. A.

    1993-04-01

    The application of powder metal (PM) superalloys in aircraft turbine engine rotating components is prompted by performance driven high strength and creep resistance requirements. Fine grain, precipitation strengthened nickel-base alloys such as IN100, Rene'95, and Rene'88DT meet these requirements up to operating temperatures in the 1200-1300F (649-704C) range. In addition to burst and deformation limits, design constraints include durability (fatigue) and damage tolerance (crack growth resistance) capability to insure reliability and safety. Fatigue life for these alloys can be influenced by inhomogeneities (inclusions) intrinsic to the microstructure as the result of processing, and by perturbations of the surface integrity during component manufacture and subsequent usage. Understanding of PM fatigue behavior and substantiation of life assessment methodology must appropriately recognize these potential influences. New testing, modeling, and analysis schemes are necessitated in engineering development programs addressing generation and validation of life prediction techniques for these materials. This paper outlines one approach to substantiating PM fatigue life prediction that attempts to recognize homogeneous fatigue initiation by incorporating probabilistic models and development testing methods that address material volume and component feature effects. Complications and limitations being addressed in ongoing work are discussed.

  14. Ceramic catalyst materials

    SciTech Connect

    Sault, A.G.; Gardner, T.J.; Hanprasopwattanna, A.; Reardon, J.; Datye, A.K.

    1995-08-01

    Hydrous titanium oxide (HTO) ion-exchange materials show great potential as ceramic catalyst supports due to an inherently high ion-exchange capacity which allows facile loading of catalytically active transition metal ions, and an ability to be cast as thin films on virtually any substrate. By coating titania and HTO materials onto inexpensive, high surface area substrates such as silica and alumina, the economics of using these materials is greatly improved, particularly for the HTO materials, which are substantially more expensive in the bulk form than other oxide supports. In addition, the development of thin film forms of these materials allows the catalytic and mechanical properties of the final catalyst formulation to be separately engineered. In order to fully realize the potential of thin film forms of titania and HTO, improved methods for the deposition and characterization of titania and HTO films on high surface area substrates are being developed. By varying deposition procedures, titania film thickness and substrate coverage can be varied from the submonolayer range to multilayer thicknesses on both silica and alumina. HTO films can also be formed, but the quality and reproducibility of these films is not nearly as good as for pure titania films. The films are characterized using a combination of isopropanol dehydration rate measurements, point of zero charge (PZC) measurements, BET surface area, transmission electron microscopy (TEM), and elemental analysis. In order to assess the effects of changes in film morphology on catalytic activity, the films are being loaded with MoO{sub 3} using either incipient wetness impregnation or ion-exchange of heptamolybdate anions followed by calcining. The MoO{sub 3} is then sulfided to form MOS{sub 2}, and tested for catalytic activity using pyrene hydrogenation and dibenzothiophene (DBT) desulfurization, model reactions that simulate reactions occurring during coal liquefaction.

  15. Discovery and application of doubly quaternized cinchona-alkaloid-based phase-transfer catalysts.

    PubMed

    Xiang, Bangping; Belyk, Kevin M; Reamer, Robert A; Yasuda, Nobuyoshi

    2014-08-04

    We report the discovery of novel N,N'-disubstituted cinchona alkaloids as efficient phase-transfer catalysts for the assembly of stereogenic quaternary centers. In comparison to traditional cinchona-alkaloid-based phase-transfer catalysts, these new catalysts afford substantial improvements in enantioselectivity and reaction rate for intramolecular spirocyclization reactions with catalyst loadings as low as 0.3 mol% under mild conditions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Design better cerium-based oxidation catalysts

    SciTech Connect

    Trovarelli, A.; Leitenburg, C. de; Dolcetti, G.

    1997-06-01

    Structural and energetic factors play an important role in the development of a new generation of automobile exhaust catalysts containing CeO{sub 2} doped with ZrO{sub 2} and/or other rare earth oxides such as PrO{sub x}, Y{sub 2}O{sub 3}, and La{sub 2}O{sub 3}. These new catalysts possess high oxygen storage capacity, improved thermal stability, and enhanced catalytic properties. These properties are discussed.

  17. Manganese dioxide as a new cathode catalyst in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Hu, Boxun; Suib, Steven; Lei, Yu; Li, Baikun

    This study focused on manganese oxides with a cryptomelane-type octahedral molecular sieve (OMS-2) structure to replace platinum as a cathode catalyst in microbial fuel cells (MFCs). Undoped (ud-OSM-2) and three catalysts doped with cobalt (Co-OMS-2), copper (Cu-OMS-2), and cerium (Ce-OMS-2) to enhance their catalytic performances were investigated. The novel OMS-2 cathodes were examined in granular activated carbon MFC (GACMFC) with sodium acetate as the anode reagent and oxygen in air as the cathode reagent. The results showed that after 400 h of operation, the Co-OMS-2 and Cu-OMS-2 exhibited good catalytic performance in an oxygen reduction reaction (ORR). The voltage of the Co-OMS-2 GACMFC was 217 mV, and the power density was 180 mW m -2. The voltage of the Cu-OMS-2 GACMFC was 214 mV and the power density was 165 mW m -2. The internal resistance (R in) of the OMS-2 GACMFCs (18 ± 1 Ω) was similar to that of the platinum GACMFCs (17 Ω). Furthermore, the degradation rates of organic substrates in the OMS-2 GACMFCs were twice those in the platinum GACMFCs, which enhance their wastewater treatment efficiencies. This study indicated that using OMS-2 manganese oxides to replace platinum as a cathodic catalyst enhances power generation, increases contaminant removal, and substantially reduces the cost of MFCs.

  18. Lewis Base Catalysts 6: Carbene Catalysts

    PubMed Central

    Moore, Jennifer L.

    2013-01-01

    The use of N-heterocyclic carbenes as catalysts for organic transformations has received increased attention in the past 10 years. A discussion of catalyst development and nucleophilic characteristics precedes a description of recent advancements and new reactions using N-heterocyclic carbenes in catalysis. PMID:21494949

  19. 29 CFR 1990.145 - Consideration of substantial new issues or substantial new evidence.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., as well as a petition to consider “substantial new evidence”. (2) Contents. Each petition for... or an Advance Notice of Proposed Rulemaking; (v) A detailed statement and analysis as to why...

  20. Deactivation of Oxidation Catalysts

    DTIC Science & Technology

    1991-05-01

    the fresh catalyst . The loss in chromium may be related to the formation of volatile chromium oxychlorde which vaporizes from the catalyst . It is...CeO2 only marginally improved the thtrmal stability. The addition of 2% water vapor inhibited the oxidation of ethanol for all three copper catalysts ...original activity. Field tests of a copper chromite catalyst on process gas containing H2S, methyl mercaptan, n-aldehydes, and furfural showed

  1. Ruthenium-based olefin metathesis catalysts bearing pH-responsive ligands: External control of catalyst solubility and activity

    NASA Astrophysics Data System (ADS)

    Balof, Shawna Lynn

    2011-12-01

    Sixteen novel, Ru-based olefin metathesis catalysts bearing pH responsive ligands were synthesized. The pH-responsive groups employed with these catalysts included dimethylamino (NMe2) modified NHC ligands as well as N-donor dimethylaminopyridine (DMAP) and 3-(o-pyridyl)propylidene ligands. These pH-responsive ligands provided the means by which the solubility and/or activity profiles of the catalysts produced could be controlled via acid addition. The main goal of this dissertation was to design catalyst systems capable of performing ring opening metathesis (ROMP) and ring closing metathesis (RCM) reactions in both organic and aqueous media. In an effort to quickly gain access to new catalyst structures, a template synthesis for functionalized NHC ligand precursors was designed, in addition to other strategies, to obtain ligand precursors with ancillary NMe2 groups. Kinetic studies for the catalysts produced from these precursors showed external control of catalyst solubility was afforded via protonation of the NMe2 groups of their NHC ligands. Additionally, this protonation afforded external control of catalyst propagation rates for several catalysts. This is the first known independent external control for the propagation rates of ROMP catalysts. The incorporation of pH-responsive N-donor ligands into catalyst structures also provided the means for the external control of metathesis activity, as the protonation of these ligands resulted in an increased initiation rate based on their fast and irreversible dissociation from the metal center. The enhanced external control makes these catalysts applicable to a wide range of applications, some of which have been explored by us and/or through collaboration. Three of the catalysts designed showed remarkable metathesis activity in aqueous media. These catalysts displayed comparable RCM activity in aqueous media to a class of water-soluble catalysts reported by Grubbs et al., considered to be the most active catalyst for

  2. Reforming with an improved platinum-containing catalyst

    SciTech Connect

    Bertolacini, R.J.; Lysholm, D.L.; Pellet, R.J.

    1982-10-12

    There is disclosed a catalyst, which catalyst comprises a physical particle-form mixture of a component A and a component B , said component A comprising one or more group VIII noble metals and a combined halogen deposed on a refractory inorganic oxide and said component B comprising a metal from group IVB or group VB of the periodic table of elements and a combined halogen deposed on a refractory inorganic oxide. Such catalyst is suitable for use in a hydrocarbon conversion reaction zone. The catalyst can be employed in a process for the reforming of a hydrocarbon stream, which process comprises contacting said stream in a reaction zone under reforming conditions and in the presence of hydrogen with said catalyst. The catalyst is not presulfided. A preferred process comprises contacting a hydrocarbon stream that contains a substantial amount of sulfur.

  3. Investigation on C-TiO2 nanotubes composite as Pt catalyst support for methanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Sui, Xu-Lei; Wang, Zhen-Bo; Yang, Min; Huo, Li; Gu, Da-Ming; Yin, Ge-Ping

    2014-06-01

    In this paper, Pt nanoparticles have been successfully deposited on the mixture of carbon black and one-dimensional self-ordered TiO2 nanotubes (TNTs) array by a microwave-assisted polyol process to synthesize Pt/C-TNTs catalyst. TiO2 nanoparticles (TNPs) are used instead of TNTs to prepare catalyst as a reference. The obtained samples are characterized by physical characterization and electrochemical measurements. The results show that Pt nanoparticles are uniformly deposited on the three-phase interfaces between carbon and TNTs. The Pt/C-TNTs possesses substantially enhanced activity and stability in electrochemical performance. Such remarkable properties are due to the excellent composite carrier of C-TNTs: (1) TNTs has strong corrosion resistance in acidic and oxidative environment and a metal support interaction between Pt and TNTs; (2) Compared to TNPs, TNTs is more suitable for electro-catalytic field on account of its better electronic conductivity; (3) Compared to TNPs, TNTs can improve the anti-poisoning ability of catalyst for methanol oxidation. (4) Amorphous carbon can improve the dispersion of platinum particles; (5) The distribution of carbon improves the poor conductivity of TNTs. These studies indicate that Pt/C-TNTs compound is a promising catalyst for methanol electrooxidation.

  4. Acetic acid effects on enhancement of growth rate and reduction of amorphous carbon deposition on CNT arrays along a growth window in a floating catalyst reactor

    NASA Astrophysics Data System (ADS)

    Maghrebi, Morteza; Khodadadi, Abbas Ali; Mortazavi, Yadollah; Sane, Ali; Rahimi, Mohsen; Shirazi, Yaser; Tsakadze, Zviad; Mhaisalkar, Subodh

    2009-11-01

    The mm-long carbon nanotube (CNT) arrays were grown in a floating catalyst reactor, using xylene-ferrocene and a small amount of acetic acid as the feed. The CNT arrays deposited on a quartz substrate at several positions along the reactor were extensively characterized using Raman spectroscopy, scanning electron microscopy, X-ray diffraction, high-resolution transmission electron microscopy, and optical microscopy. Various characterization methods consistently reveal that the acetic acid additive to the feed alleviates deposition of amorphous carbon layer, which gradually thickens CNTs along the reactor. The acetic acid also resulted in a higher growth rate along the so-called growth window, where CNT arrays are deposited on the quartz substrate. High-performance liquid chromatography of extracted byproducts (PAHs) confirmed the presence of some polycyclic aromatic hydrocarbons. The solid weight of PAHs decreased upon addition of ferrocene as the catalyst precursor, as well as of acetic acid to xylene feed. The results suggest that primary light products of xylene pyrolysis can be competitive reactants for both catalytic and subsequent pyrolytic reactions. They may also be more efficient feeds for CNT growth than xylene itself.

  5. Cobalt promoted copper manganese oxide catalysts for ambient temperature carbon monoxide oxidation.

    PubMed

    Jones, Christopher; Taylor, Stuart H; Burrows, Andrew; Crudace, Mandy J; Kiely, Christopher J; Hutchings, Graham J

    2008-04-14

    Low levels of cobalt doping (1 wt%) of copper manganese oxide enhances its activity for carbon monoxide oxidation under ambient conditions and the doped catalyst can display higher activity than current commercial catalysts.

  6. Hierarchical Mesoporous/Macroporous Perovskite La0.5Sr0.5CoO3-x Nanotubes: A Bifunctional Catalyst with Enhanced Activity and Cycle Stability for Rechargeable Lithium Oxygen Batteries.

    PubMed

    Liu, Guoxue; Chen, Hongbin; Xia, Lu; Wang, Suqing; Ding, Liang-Xin; Li, Dongdong; Xiao, Kang; Dai, Sheng; Wang, Haihui

    2015-10-14

    Perovskites show excellent specific catalytic activity toward both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline solutions; however, small surface areas of the perovskites synthesized by traditional sol-gel methods lead to low utilization of catalytic sites, which gives rise to poor Li-O2 batteries performance and restricts their application. Herein, a hierarchical mesporous/macroporous perovskite La0.5Sr0.5CoO3-x (HPN-LSC) nanotube is developed to promote its application in Li-O2 batteries. The HPN-LSC nanotubes were synthesized via electrospinning technique followed by postannealing. The as-prepared HPN-LSC catalyst exhibits outstanding intrinsic ORR and OER catalytic activity. The HPN-LSC/KB electrode displays excellent performance toward both discharge and charge processes for Li-O2 batteries, which enhances the reversibility, the round-trip efficiency, and the capacity of resultant batteries. The synergy of high catalytic activity and hierarchical mesoporous/macroporous nanotubular structure results in the Li-O2 batteries with good rate capability and excellent cycle stability of sustaining 50 cycles at a current density of 0.1 mA cm(-2) with an upper-limit capacity of 500 mAh g(-1). The results will benefit for the future development of high-performance Li-O2 batteries using hierarchical mesoporous/macroporous nanostructured perovskite-type catalysts.

  7. Communication: Enhanced oxygen reduction reaction and its underlying mechanism in Pd-Ir-Co trimetallic alloys

    SciTech Connect

    Ham, Hyung Chul; Hwang, Gyeong S.; Manogaran, Dhivya; Lee, Kang Hee; Jin, Seon-ah; You, Dae Jong; Pak, Chanho; Kwon, Kyungjung

    2013-11-28

    Based on a combined density functional theory and experimental study, we present that the electrochemical activity of Pd{sub 3}Co alloy catalysts toward oxygen reduction reaction (ORR) can be enhanced by adding a small amount of Ir. While Ir tends to favorably exist in the subsurface layers, the underlying Ir atoms are found to cause a substantial modification in the surface electronic structure. As a consequence, we find that the activation barriers of O/OH hydrogenation reactions are noticeably lowered, which would be mainly responsible for the enhanced ORR activity. Furthermore, our study suggests that the presence of Ir in the near-surface region can suppress Co out-diffusion from the Pd{sub 3}Co substrate, thereby improving the durability of Pd-Ir-Co catalysts. We also discuss the relative roles played by Ir and Co in enhancing the ORR activity relative to monometallic Pd catalysts.

  8. New catalysts improves heavy feedstock hydro-cracking

    SciTech Connect

    Hoek, A.; Huizinga, T.; Esener, A.A.; Maxwell, I.E.; Stork, W. ); van de Meerakker, F.J. ); Sy, O. )

    1991-04-22

    A new zeolite-Y-based second-stage hydrocracking catalyst, designated S-703, has been developed by Shell. Laboratory testing and commercial use show it has significantly improved performance with respect to gas make and middle-distillate selectivity in processing heavy feedstocks when compared to a Shell catalyst, S-753, developed earlier. Further, the new catalyst exhibits enhanced stability. Extensive laboratory testing of the S-703 catalyst has been carried out under single-stage, stacked- bed, two-stage-flow, and series-flow conditions. Commercial experience with the new catalyst has now been obtained in several units. To date, the commercial results have confirmed the laboratory results in terms of the superior, heavy- feedstock processing performance of the new catalyst in all respects. Because the trend toward heavier feedstocks is expected to continue, it is likely that catalysts such as S- 703 will find increasing applications in hydrocrackers in the future.

  9. Environmentally benign production of biodiesel using heterogeneous catalysts.

    PubMed

    Hara, Michikazu

    2009-01-01

    Fuelling the future: The production of esters of higher fatty acids from plant materials is of great interest for the manufacture of biodiesel. Heterogeneous catalysts can provide new routes for the environmentally benign production of biodiesel. Particulate heterogeneous catalysts can be readily separated from products following reaction allowing the catalyst to be reused, generating less waste, and consuming less energy. Diesel engines are simple and powerful, and exhibit many advantages in energy efficiency and cost. Therefore, the production of higher fatty acid esters from plant materials has become of interest in recent years for the manufacture of biodiesel, a clean-burning alternative fuel. The industrial production of biodiesel mostly proceeds in the presence of "soluble" catalysts such as alkali hydroxides and liquid acids. A considerable amount of energy is required for the purification of products and catalyst separation, and furthermore these catalysts are not reusable. This process results in substantial energy wastage and the production of large amounts of chemical waste. Particulate heterogeneous catalysts can be readily separated from products following reaction, allowing the catalyst to be reused and consuming less energy. This Minireview describes the environmentally benign production of biodiesel using heterogeneous catalysts such as solid bases, acid catalysts, and immobilized enzymes.

  10. EARLY CHILDHOOD INVESTMENTS SUBSTANTIALLY BOOST ADULT HEALTH

    PubMed Central

    Campbell, Frances; Conti, Gabriella; Heckman, James J.; Moon, Seong Hyeok; Pinto, Rodrigo; Pungello, Elizabeth; Pan, Yi

    2014-01-01

    High-quality early childhood programs have been shown to have substantial benefits in reducing crime, raising earnings, and promoting education. Much less is known about their benefits for adult health. We report the long-term health impacts of one of the oldest and most heavily cited early childhood interventions with long-term follow-up evaluated by the method of randomization: the Carolina Abecedarian Project (ABC). Using recently collected biomedical data, we find that disadvantaged children randomly assigned to treatment have significantly lower prevalence of risk factors for cardiovascular and metabolic diseases in their mid-30s. The evidence is especially strong for males. The mean systolic blood pressure among the control males is 143, while only 126 among the treated. One in four males in the control group is affected by metabolic syndrome, while none in the treatment group is. To reach these conclusions, we address several statistical challenges. We use exact permutation tests to account for small sample sizes and conduct a parallel bootstrap confidence interval analysis to confirm the permutation analysis. We adjust inference to account for the multiple hypotheses tested and for nonrandom attrition. Our evidence shows the potential of early life interventions for preventing disease and promoting health. PMID:24675955

  11. Substantial nitrogen pollution embedded in international trade

    NASA Astrophysics Data System (ADS)

    Oita, Azusa; Malik, Arunima; Kanemoto, Keiichiro; Geschke, Arne; Nishijima, Shota; Lenzen, Manfred

    2016-02-01

    Anthropogenic emissions of reactive nitrogen to the atmosphere and water bodies can damage human health and ecosystems. As a measure of a nation’s contribution to this potential damage, a country’s nitrogen footprint has been defined as the quantity of reactive nitrogen emitted during the production, consumption and transportation of commodities consumed within that country, whether those commodities are produced domestically or internationally. Here we use global emissions databases, a global nitrogen cycle model, and a global input-output database of domestic and international trade to calculate the nitrogen footprints for 188 countries as the sum of emissions of ammonia, nitrogen oxides and nitrous oxide to the atmosphere, and of nitrogen potentially exportable to water bodies. Per-capita footprints range from under 7 kg N yr-1 in some developing countries to over 100 kg N yr-1 in some wealthy nations. Consumption in China, India, the United States and Brazil is responsible for 46% of global emissions. Roughly a quarter of the global nitrogen footprint is from commodities that were traded across country borders. The main net exporters have significant agricultural, food and textile exports, and are often developing countries, whereas important net importers are almost exclusively developed economies. We conclude that substantial local nitrogen pollution is driven by demand from consumers in other countries.

  12. Substantial global carbon uptake by cement carbonation

    NASA Astrophysics Data System (ADS)

    Xi, Fengming; Davis, Steven J.; Ciais, Philippe; Crawford-Brown, Douglas; Guan, Dabo; Pade, Claus; Shi, Tiemao; Syddall, Mark; Lv, Jie; Ji, Lanzhu; Bing, Longfei; Wang, Jiaoyue; Wei, Wei; Yang, Keun-Hyeok; Lagerblad, Björn; Galan, Isabel; Andrade, Carmen; Zhang, Ying; Liu, Zhu

    2016-12-01

    Calcination of carbonate rocks during the manufacture of cement produced 5% of global CO2 emissions from all industrial process and fossil-fuel combustion in 2013. Considerable attention has been paid to quantifying these industrial process emissions from cement production, but the natural reversal of the process--carbonation--has received little attention in carbon cycle studies. Here, we use new and existing data on cement materials during cement service life, demolition, and secondary use of concrete waste to estimate regional and global CO2 uptake between 1930 and 2013 using an analytical model describing carbonation chemistry. We find that carbonation of cement materials over their life cycle represents a large and growing net sink of CO2, increasing from 0.10 GtC yr-1 in 1998 to 0.25 GtC yr-1 in 2013. In total, we estimate that a cumulative amount of 4.5 GtC has been sequestered in carbonating cement materials from 1930 to 2013, offsetting 43% of the CO2 emissions from production of cement over the same period, not including emissions associated with fossil use during cement production. We conclude that carbonation of cement products represents a substantial carbon sink that is not currently considered in emissions inventories.

  13. Early childhood investments substantially boost adult health.

    PubMed

    Campbell, Frances; Conti, Gabriella; Heckman, James J; Moon, Seong Hyeok; Pinto, Rodrigo; Pungello, Elizabeth; Pan, Yi

    2014-03-28

    High-quality early childhood programs have been shown to have substantial benefits in reducing crime, raising earnings, and promoting education. Much less is known about their benefits for adult health. We report on the long-term health effects of one of the oldest and most heavily cited early childhood interventions with long-term follow-up evaluated by the method of randomization: the Carolina Abecedarian Project (ABC). Using recently collected biomedical data, we find that disadvantaged children randomly assigned to treatment have significantly lower prevalence of risk factors for cardiovascular and metabolic diseases in their mid-30s. The evidence is especially strong for males. The mean systolic blood pressure among the control males is 143 millimeters of mercury (mm Hg), whereas it is only 126 mm Hg among the treated. One in four males in the control group is affected by metabolic syndrome, whereas none in the treatment group are affected. To reach these conclusions, we address several statistical challenges. We use exact permutation tests to account for small sample sizes and conduct a parallel bootstrap confidence interval analysis to confirm the permutation analysis. We adjust inference to account for the multiple hypotheses tested and for nonrandom attrition. Our evidence shows the potential of early life interventions for preventing disease and promoting health.

  14. Catalyst by Design

    SciTech Connect

    Narula, Chaitanya Kumar; DeBusk, Melanie Moses

    2014-01-01

    The development of new catalytic materials is still dominated by trial and error methods. Although it has been successful, the empirical development of catalytic materials is time consuming and expensive with no guarantee of success. In our laboratories, we are developing a comprehensive catalysts by design that involves state-of-the-art first principle density functional theory calculations, experimental design of catalyst sites, and sub- ngstr m resolution imaging with an aberration-corrected electron microscope to characterize the microstructure. In this chapter, we focus on supported platinum cluster catalyst systems which are one of the most important industrial catalysts and attempt to demonstrate the feasibility of the catalyst by design concept.

  15. System for reactivating catalysts

    SciTech Connect

    Ginosar, Daniel M.; Thompson, David N.; Anderson, Raymond P.

    2010-03-02

    A method of reactivating a catalyst, such as a solid catalyst or a liquid catalyst is provided. The method comprises providing a catalyst that is at least partially deactivated by fouling agents. The catalyst is contacted with a fluid reactivating agent that is at or above a critical point of the fluid reactivating agent and is of sufficient density to dissolve impurities. The fluid reactivating agent reacts with at least one fouling agent, releasing the at least one fouling agent from the catalyst. The at least one fouling agent becomes dissolved in the fluid reactivating agent and is subsequently separated or removed from the fluid reactivating agent so that the fluid reactivating agent may be reused. A system for reactivating a catalyst is also disclosed.

  16. Photoelectrochemical water oxidation by cobalt catalyst ("Co-Pi")/alpha-Fe(2)O(3) composite photoanodes: oxygen evolution and resolution of a kinetic bottleneck.

    PubMed

    Zhong, Diane K; Gamelin, Daniel R

    2010-03-31

    A cobalt-phosphate water oxidation catalyst ("Co-Pi") has been electrodeposited onto mesostructured alpha-Fe(2)O(3) photoanodes. The photoelectrochemical properties of the resulting composite photoanodes were optimized for solar water oxidation under frontside illumination in pH 8 electrolytes. A kinetic bottleneck limiting the performance of such photoanodes was identified and shown to be largely overcome by more sparse deposition of Co-Pi onto the alpha-Fe(2)O(3). Relative to alpha-Fe(2)O(3) photoanodes, a sustained 5-fold enhancement in the photocurrent density and O(2) evolution rate was observed at +1.0 V vs RHE with the Co-Pi/alpha-Fe(2)O(3) composite photoanodes. These results demonstrate that integration of this promising water oxidation catalyst with a photon-absorbing substrate can provide a substantial reduction in the external power needed to drive the catalyst's electrolysis chemistry.

  17. Synergistic effect of carbon nanofiber/nanotube composite catalyst on carbon felt electrode for high-performance all-vanadium redox flow battery.

    PubMed

    Park, Minjoon; Jung, Yang-jae; Kim, Jungyun; Lee, Ho il; Cho, Jeaphil

    2013-10-09

    Carbon nanofiber/nanotube (CNF/CNT) composite catalysts grown on carbon felt (CF), prepared from a simple way involving the thermal decomposition of acetylene gas over Ni catalysts, are studied as electrode materials in a vanadium redox flow battery. The electrode with the composite catalyst prepared at 700 °C (denoted as CNF/CNT-700) demonstrates the best electrocatalytic properties toward the V(2+)/V(3+) and VO(2+)/VO2(+) redox couples among the samples prepared at 500, 600, 700, and 800 °C. Moreover, this composite electrode in the full cell exhibits substantially improved discharge capacity and energy efficiency by ~64% and by ~25% at 40 mA·cm(-2) and 100 mA·cm(-2), respectively, compared to untreated CF electrode. This outstanding performance is due to the enhanced surface defect sites of exposed edge plane in CNF and a fast electron transfer rate of in-plane side wall of the CNT.

  18. Membrane electrode assembly with enhanced platinum utilization for high temperature proton exchange membrane fuel cell prepared by catalyst coating membrane method

    NASA Astrophysics Data System (ADS)

    Liang, Huagen; Su, Huaneng; Pollet, Bruno G.; Linkov, Vladimir; Pasupathi, Sivakumar

    2014-11-01

    In this work, membrane electrode assemblies (MEAs) prepared by catalyst coating membrane (CCM) method are investigated for reduced platinum (Pt) loading and improved Pt utilization of high temperature proton exchange membrane fuel cell (PEMFC) based on phosphoric acid (PA)-doped poly(2,5-benzimidazole) (AB-PBI) membrane. The results show that CCM method exhibits significantly higher cell performance and Pt-specific power density than that of MEAs prepared with conventional gas diffusion electrode (GDE) under a low Pt loading level. In-suit cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) show that the MEAs prepared by the CCM method have a higher electrochemical surface area (ECSA), low cell ohmic resistance and low charge transfer resistance as compared to those prepared with GDEs at the same Pt loading.

  19. Enhancement of photocatalytic activity in reducing CO2 over CdS/g-C3N4 composite catalysts under UV light irradiation

    NASA Astrophysics Data System (ADS)

    Yang, Xiaoxiao; Xin, Weiyue; Yin, Xiaohong; Shao, Xiao

    2016-05-01

    The polymeric graphite-like carbon nitride (g-C3N4) and CdS/g-C3N4 composites of different mass fractions were synthesized via polycondensation and hydrothermal methods, respectively. XRD, SEM-EDS, TEM, UV-vis and PL were applied to characterize the structure, morphology and optical properties of the as-prepared CdS/g-C3N4 composites. The photocatalytic activities of the catalysts were evaluated by the reduction of CO2 in methanol solution to form methyl formate. The results indicated that the photocatalytic activities of the CdS/g-C3N4 composites were improved significantly compared with that of the pure CdS and g-C3N4. The highest activity appeared at mass ratio 1:2 of CdS:g-C3N4.

  20. Catalyst patterning for nanowire devices

    NASA Technical Reports Server (NTRS)

    Li, Jun (Inventor); Cassell, Alan M. (Inventor); Han, Jie (Inventor)

    2004-01-01

    Nanowire devices may be provided that are based on carbon nanotubes or single-crystal semiconductor nanowires. The nanowire devices may be formed on a substrate. Catalyst sites may be formed on the substrate. The catalyst sites may be formed using lithography, thin metal layers that form individual catalyst sites when heated, collapsible porous catalyst-filled microscopic spheres, microscopic spheres that serve as masks for catalyst deposition, electrochemical deposition techniques, and catalyst inks. Nanowires may be grown from the catalyst sites.

  1. Development of a stable cobalt-ruthenium Fisher-Tropsch catalyst. Final report

    SciTech Connect

    Frame, R.R.; Gala, H.B.

    1995-02-01

    The reverse micelle catalyst preparation method has been used to prepare catalysts on four supports: magnesium oxide, carbon, alumina- titania and steamed Y zeolite. These catalysts were not as active as a reference catalyst prepared during previous contracts to Union Carbide Corp. This catalyst was supported on steamed Y zerolite support and was impregnated by a pore-filling method using a nonaqueous solvent. Additional catalysts were prepared via pore- filling impregnation of steamed Y zeolites. These catalysts had levels of cobalt two to three and a half times as high as the original Union Carbide catalyst. On a catalyst volume basis they were much more active than the previous catalyst; on an atom by atom basis the cobalt was about of the same activity, i.e., the high cobalt catalysts` cobalt atoms were not extensively covered over and deactivated by other cobalt atoms. The new, high activity, Y zerolite catalysts were not as stable as the earlier Union Carbide catalyst. However, stability enhancement of these catalysts should be possible, for instance, through adjustment of the quantity and/or type of trace metals present. A primary objective of this work was determination whether small amounts of ruthenium could enhance the activity of the cobalt F-T catalyst. The reverse micelle catalysts were not activated by ruthenium, indeed scanning transmission electronic microscopy (STEM) analysis provided some evidence that ruthenium was not present in the cobalt crystallites. Ruthenium did not seem to activate the high cobalt Y zeolite catalyst either, but additional experiments with Y zeolite-supported catalysts are required. Should ruthenium prove not to be an effective promoter under the simple catalyst activation procedure used in this work, more complex activation procedures have been reported which are claimed to enhance the cobalt/ruthenium interaction and result in activity promotion by ruthenium.

  2. STUDY OF SOLVENT AND CATALYST INTERACTIONS IN DIRECT COAL LIQUEFACTION

    SciTech Connect

    Michael T. Klein

    1998-10-01

    Major objectives of the present project are to develop a better understanding of the roles of the catalyst and the liquefaction solvent in the coal liquefaction process. An open question concerning the role of the catalyst is whether intimate contact between the catalyst and the coal particles is important or required. To answer this question, it had been planned to coat an active catalyst with a porous silica coating which was found to retain catalyst activity while preventing actual contact between catalyst and coal. Consultation with people in DuPont who coat catalysts for increasing abrasion resistance have indicated that only portions of the catalyst are coated by their process (spray drying) and that sections of uncoated catalyst remain. For that reason, it was decided to suspend the catalyst in a basket separated from the coal in the reactor. The basket walls were to be permeable to the liquefaction solvent but not to the coal particles. Several such baskets were constructed of stainless steel with holes which would not permit passage of coal particles larger than 30 mesh. Liquefactions run with the coal of greater than 30 mesh size gave normal conversion of coal to liquid in the absence of catalyst in the basket, but substantially increased conversion when Ni/Mo on alumina catalyst was in the basket. While this result is interesting and suggestive of some kind of mass transfer of soluble material occurring between the catalyst and the coal, it does not eliminate the possibility of breakdown of the coal particle into particle sizes permeable to the basket. Indeed, a small amount of fine coal has been found inside the basket. To determine whether fine coal from breakdown of the coal particles is responsible for the conversion, a new basket is being prepared with 0.5{micro}m pore size.

  3. Textured catalysts and methods of making textured catalysts

    DOEpatents

    Werpy, Todd; Frye, Jr., John G.; Wang, Yong; Zacher, Alan H.

    2007-03-06

    A textured catalyst having a hydrothermally-stable support, a metal oxide and a catalyst component is described. Methods of conducting aqueous phase reactions that are catalyzed by a textured catalyst are also described. The invention also provides methods of making textured catalysts and methods of making chemical products using a textured catalyst.

  4. Recombination Catalysts for Hypersonic Fuels

    NASA Technical Reports Server (NTRS)

    Chinitz, W.

    1998-01-01

    The goal of commercially-viable access to space will require technologies that reduce propulsion system weight and complexity, while extracting maximum energy from the products of combustion. This work is directed toward developing effective nozzle recombination catalysts for the supersonic and hypersonic aeropropulsion engines used to provide such access to space. Effective nozzle recombination will significantly reduce rk=le length (hence, propulsion system weight) and reduce fuel requirements, further decreasing the vehicle's gross lift-off weight. Two such catalysts have been identified in this work, barium and antimony compounds, by developing chemical kinetic reaction mechanisms for these materials and determining the engine performance enhancement for a typical flight trajectory. Significant performance improvements are indicated, using only 2% (mole or mass) of these compounds in the combustor product gas.

  5. Process for the regeneration of metallic catalysts

    DOEpatents

    Katzer, James R.; Windawi, Hassan

    1981-01-01

    A method for the regeneration of metallic hydrogenation catalysts from the class consisting of Ni, Rh, Pd, Ir, Pt and Ru poisoned with sulfur, with or without accompanying carbon deposition, comprising subjecting the catalyst to exposure to oxygen gas in a concentration of about 1-10 ppm. intermixed with an inert gas of the group consisting of He, A, Xe, Kr, N.sub.2 and air substantially free of oxygen to an extent such that the total oxygen molecule throughout is in the range of about 10 to 20 times that of the hydrogen sulfide molecular exposure producing the catalyst poisoning while maintaining the temperature in the range of about 300.degree. to 500.degree. C.

  6. Methods of making textured catalysts

    DOEpatents

    Werpy, Todd [West Richland, WA; Frye, Jr., John G.; Wang, Yong [Richland, WA; Zacher, Alan H [Kennewick, WA

    2010-08-17

    A textured catalyst having a hydrothermally-stable support, a metal oxide and a catalyst component is described. Methods of conducting aqueous phase reactions that are catalyzed by a textured catalyst are also described. The invention also provides methods of making textured catalysts and methods of making chemical products using a textured catalyst.

  7. Catalyst Alloys Processing

    NASA Astrophysics Data System (ADS)

    Tan, Xincai

    2014-10-01

    Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

  8. Catalyst for Carbon Monoxide Oxidation

    NASA Technical Reports Server (NTRS)

    Davis, Patricia; Brown, Kenneth; VanNorman, John; Brown, David; Upchurch, Billy; Schryer, David; Miller, Irvin

    2010-01-01

    catalyst composition in an amount of about 5 to 25 (especially 7) percent by weight, SnO2 is present in an amount of about 30 to 40 (especially 40) percent by weight, and silica gel is present in an amount of 45 to 55 (especially 50) percent by weight. The composition of this catalyst was suggested by preliminary experiments in which a Pt/SnO2 catalyst was needed for bound water to enhance its activity. These experimental results suggested that if the water were bound to the surface, this water would enhance and prolong catalyst activity for long time periods. Because the catalyst is to be exposed to a laser gas mixture, and because a CO2 laser can tolerate only a very small amount of moisture, a hygroscopic support for the catalyst would provide the needed H2O into the gas. Silica gel is considered to be superior because of its property to chemisorb water on its surface over a wide range of moisture content.

  9. Methanol Oxidation Using Ozone on Titania-Supported Vanadium Catalyst

    EPA Science Inventory

    Ozone-enhanced catalytic oxidation of methanol has been conducted at mild temperatures of 100 to 250NC using V2O5/TiO2 catalyst prepared by the sol-gel method. The catalyst was characterized using XRD, surface area measurements, and temperature-programmed desorption of methanol. ...

  10. Methanol Oxidation Using Ozone on Titania-Supported Vanadium Catalyst

    EPA Science Inventory

    Ozone-enhanced catalytic oxidation of methanol has been conducted at mild temperatures of 100 to 250NC using V2O5/TiO2 catalyst prepared by the sol-gel method. The catalyst was characterized using XRD, surface area measurements, and temperature-programmed desorption of methanol. ...

  11. Development of improved iron Fischer-Tropsch catalysts

    SciTech Connect

    Bukur, D.B.

    1992-01-10

    The objective of proposed research is development of catalysts with enhanced slurry phase activity and better selectivity to fuel range products, through a more detailed understanding and systematic studies of the effects of pretreatment procedures and promoters/binders (silica) on catalyst performance.

  12. Development of improved iron Fischer-Tropsch catalysts

    SciTech Connect

    Bukur, D.B.

    1990-06-17

    The objective of proposed research is development of catalysts with enhanced slurry phase activity and better selectivity to fuel range products, through a more detailed understanding and systematic studies of the effects of pretreatment procedures and promoters/binders (silica) on catalyst performance.

  13. Development of improved iron Fischer-Tropsch catalysts

    SciTech Connect

    Bukur, D.B.; Patel, S.A.; Dalai, A.K.; Jayanthi, G.; Ledakowicz, S.

    1990-04-30

    The objective of proposed research is development of catalysts with enhanced slurry phase activity and better selectivity to fuel range products, through a more detailed understanding and systematic studies of the effects of pretreatment procedures and promoters/binders (silica) on catalyst performance.

  14. Enhanced photocatalytic activity of hydrothermally grown BiFeO3 nanostructures and role of catalyst recyclability in photocatalysis based on magnetic framework

    NASA Astrophysics Data System (ADS)

    Dhanalakshmi, Radhalayam; Muneeswaran, M.; Vanga, Pradeep Reddy; Ashok, M.; Giridharan, N. V.

    2016-01-01

    The photocatalytic activity of bismuth ferrite (BiFeO3: BFO) nanostructures on the degradation of methyl violet 2B (MV) is demonstrated for the first time under sunlight irradiation with the efficiency of 97.6 %. The photocatalytic BFO nanostructures have been successfully synthesized through hydrothermal method. Initial characterization of BFO nanostructures such as structural, functional, morphological, optical, and magnetic properties has been performed. From the X-ray diffraction analysis, the synthesized nanostructures are found to have rhombohedral structure with R3c space group confirmed by Rietveld analysis. The formation of perovskite structure is confirmed through FTIR analysis. Nanostructures were found to have rod-like morphology with the length between 15 and 20 nm and diameter of about 2-3 nm measured through HR-TEM. The surface area and N2 adsorption-desorption isotherms have been preformed through BET analysis. The optical band gap investigation shows that the E g value of BFO is about 2.1 eV. The magnetization measurements revealed a weak ferromagnetic behavior at room temperature, and the same has been confirmed through ABK plot. The photocatalytic activity of BFO is tested on the degradation of harmful MV dye under the irradiation of direct sunlight, influences of oxygen, and hydrogen peroxide. The photodecomposition kinetics of MV has been described through Langmuir-Hinshelwood model. The stability and recyclability of catalyst have also been studied.

  15. Metal-Organic Framework Templated Synthesis of Ultrasmall Catalyst Loaded ZnO/ZnCo2O4 Hollow Spheres for Enhanced Gas Sensing Properties

    PubMed Central

    Koo, Won-Tae; Choi, Seon-Jin; Jang, Ji-Soo; Kim, Il-Doo

    2017-01-01

    To achieve the rational design of nanostructures for superior gas sensors, the ultrasmall nanoparticles (NPs) loaded on ternary metal oxide (TMO) hollow spheres (HS) were synthesized by using the polystyrene (PS) sphere template and bimetallic metal-organic framework (BM-MOFs) mold. The zinc and cobalt based zeolite imidazole frameworks (BM-ZIFs) encapsulating ultrasmall Pd NPs (2–3 nm) were assembled on PS spheres at room temperature. After calcination at 450 °C, these nanoscale Pd particles were effectively infiltrated on the surface of ZnO/ZnCo2O4 HSs. In addition, the heterojunctions of Pd-ZnO, Pd-ZnCo2O4, and ZnO-ZnCo2O4 were formed on each phase. The synthesized Pd-ZnO/ZnCo2O4 HSs exhibited extremely high selectivity toward acetone gas with notable sensitivity (S = 69% to 5 ppm at 250 °C). The results demonstrate that MOF driven ultrasmall catalyst loaded TMO HSs were highly effective platform for high performance chemical gas sensors. PMID:28327599

  16. Enhanced performance of polybenzimidazole-based high temperature proton exchange membrane fuel cell with gas diffusion electrodes prepared by automatic catalyst spraying under irradiation technique

    NASA Astrophysics Data System (ADS)

    Su, Huaneng; Pasupathi, Sivakumar; Bladergroen, Bernard Jan; Linkov, Vladimir; Pollet, Bruno G.

    2013-11-01

    Gas diffusion electrodes (GDEs) prepared by a novel automatic catalyst spraying under irradiation (ACSUI) technique are investigated for improving the performance of phosphoric acid (PA)-doped polybenzimidazole (PBI) high temperature proton exchange membrane fuel cell (PEMFC). The physical properties of the GDEs are characterized by pore size distribution and scanning electron microscopy (SEM). The electrochemical properties of the membrane electrode assembly (MEA) with the GDEs are evaluated and analyzed by polarization curve, cyclic voltammetry (CV) and electrochemistry impedance spectroscopy (EIS). Effects of PTFE binder content, PA impregnation and heat treatment on the GDEs are investigated to determine the optimum performance of the single cell. At ambient pressure and 160 °C, the maximum power density can reach 0.61 W cm-2, and the current density at 0.6 V is up to 0.38 A cm-2, with H2/air and a platinum loading of 0.5 mg cm-2 on both electrodes. The MEA with the GDEs shows good stability for fuel cell operating in a short term durability test.

  17. Metal-Organic Framework Templated Synthesis of Ultrasmall Catalyst Loaded ZnO/ZnCo2O4 Hollow Spheres for Enhanced Gas Sensing Properties

    NASA Astrophysics Data System (ADS)

    Koo, Won-Tae; Choi, Seon-Jin; Jang, Ji-Soo; Kim, Il-Doo

    2017-03-01

    To achieve the rational design of nanostructures for superior gas sensors, the ultrasmall nanoparticles (NPs) loaded on ternary metal oxide (TMO) hollow spheres (HS) were synthesized by using the polystyrene (PS) sphere template and bimetallic metal-organic framework (BM-MOFs) mold. The zinc and cobalt based zeolite imidazole frameworks (BM-ZIFs) encapsulating ultrasmall Pd NPs (2–3 nm) were assembled on PS spheres at room temperature. After calcination at 450 °C, these nanoscale Pd particles were effectively infiltrated on the surface of ZnO/ZnCo2O4 HSs. In addition, the heterojunctions of Pd-ZnO, Pd-ZnCo2O4, and ZnO-ZnCo2O4 were formed on each phase. The synthesized Pd-ZnO/ZnCo2O4 HSs exhibited extremely high selectivity toward acetone gas with notable sensitivity (S = 69% to 5 ppm at 250 °C). The results demonstrate that MOF driven ultrasmall catalyst loaded TMO HSs were highly effective platform for high performance chemical gas sensors.

  18. Novel quantum dot and nano-sheet TiO2 (B) composite for enhanced photocatalytic H2 - Production without Co-Catalyst

    NASA Astrophysics Data System (ADS)

    Si, Jingjing; Wang, Yu; Xia, Xiaohong; Peng, Shuai; Wang, Ying; Xiao, Shuying; Zhu, Lingbin; Bao, Yuwen; Huang, Zhongbing; Gao, Yun

    2017-08-01

    Recently, the production of hydrogen through water splitting using titania (TiO2) as photocatalyst has received great attention in the new energy field. In this work, a single one-step hydrothermal method is used to synthesize ultra-thin TiO2 (B) nano-sheets, anatase TiO2, and their composite, using ethylene glycol (EG) and ethanol as the solvent. A new composite nanostructure with anatase TiO2 quantum dots grown on TiO2 (B) nano-sheets is obtained at certain ratios between EG and ethanol. Even without the help of co-catalyst, a high photocatalytic efficiency, about 45 times of that of rutile-anatase mixed Degussa P25, is observed in the TiO2 (B)-anatase composite nanostructure. The outstanding performance can be attributed to its large specific surface area, abundant surface active sites, mixed phase promoted efficient charge separation. Moreover, the properly aligned band structure, with the conduction band level of ultra-thin TiO2 (B) about 0.6 eV higher than that of the anatase, provides a large driving force for the reduction of water.

  19. Nickel and iron pincer complexes as catalysts for the reduction of carbonyl compounds.

    PubMed

    Chakraborty, Sumit; Bhattacharya, Papri; Dai, Huiguang; Guan, Hairong

    2015-07-21

    The reductions of aldehydes, ketones, and esters to alcohols are important processes for the synthesis of chemicals that are vital to our daily life, and the reduction of CO2 to methanol is expected to provide key technology for carbon management and energy storage in our future. Catalysts that affect the reduction of carbonyl compounds often contain ruthenium, osmium, or other precious metals. The high and fluctuating price, and the limited availability of these metals, calls for efforts to develop catalysts based on more abundant and less expensive first-row transition metals, such as nickel and iron. The challenge, however, is to identify ligand systems that can increase the thermal stability of the catalysts, enhance their reactivity, and bypass the one-electron pathways that are commonly observed for first-row transition metal complexes. Although many other strategies exist, this Account describes how we have utilized pincer ligands along with other ancillary ligands to accomplish these goals. The bis(phosphinite)-based pincer ligands (also known as POCOP-pincer ligands) create well-defined nickel hydride complexes as efficient catalysts for the hydrosilylation of aldehydes and ketones and the hydroboration of CO2 to methanol derivatives. The hydride ligands in these complexes are substantially nucleophilic, largely due to the enhancement by the strongly trans-influencing aryl groups. Under the same principle, the pincer-ligated nickel cyanomethyl complexes exhibit remarkably high activity (turnover numbers up to 82,000) for catalytically activating acetonitrile and the addition of H-CH2CN across the C═O bonds of aldehydes without requiring a base additive. Cyclometalation of bis(phosphinite)-based pincer ligands with low-valent iron species "Fe(PR3)4" results in diamagnetic Fe(II) hydride complexes, which are active catalysts for the hydrosilylation of aldehydes and ketones. Mechanistic investigation suggests that the hydride ligand is not delivered to the

  20. METHOD OF PURIFYING CATALYSTS

    DOEpatents

    Joris, G.G.

    1958-09-01

    It has been fuund that the presence of chlorine as an impurity adversely affects the performance of finely divided platinum catalysts such as are used in the isotopic exchange process for the production of beavy water. This chlorine impurity may be removed from these catalysts by treating the catalyst at an elevated temperature with dry hydrogen and then with wet hydrogen, having a hydrogen-water vapor volume of about 8: 1. This alternate treatment by dry hydrogen and wet hydrogen is continued until the chlorine is largely removed from the catalyst.

  1. Polyolefin catalyst manufacturing

    SciTech Connect

    Inkrott, K.E.; Scinta, J.; Smith, P.D. )

    1989-10-16

    Statistical process control (SPC) procedures are absolutely essential for making new-generation polyolefin catalysts with the consistent high quality required by modern polyolefin processes. Stringent quality assurance is critical to the production of today's high-performance catalysts. Research and development efforts during the last 20 years have led to major technological improvements in the polyolefin industry. New generation catalysts, which once were laboratory curiosities, must now be produced commercially on a regular and consistent basis to meet the increasing requirements of the plastics manufacturing industry. To illustrate the more stringent requirements for producing the new generation polyolefin catalysts, the authors compare the relatively simple, first-generation polypropylene catalyst production requirements with some of the basic requirements of manufacturing a more complex new-generation catalyst, such as Catalyst Resources Inc.'s LYNX 900. The principles which hold true for the new-generation catalysts such as LYNX 900 are shown to apply equally to the scale-up of other advanced technology polyolefin catalysts.

  2. Liquefaction with microencapsulated catalysts

    DOEpatents

    Weller, Sol W.

    1985-01-01

    A method of dispersing a liquefaction catalyst within coal or other carbonaceous solids involves providing a suspension in oil of microcapsules containing the catalyst. An aqueous solution of a catalytic metal salt is emulsified in the water-immiscible oil and the resulting minute droplets microencapsulated in polymeric shells by interfacial polycondensation. The catalyst is subsequently blended and dispersed throughout the powdered carbonaceous material to be liquefied. At liquefaction temperatures the polymeric microcapsules are destroyed and the catalyst converted to minute crystallites in intimate contact with the carbonaceous material.

  3. Spontaneous Pt Deposition on Defective Surfaces of In2O3 Nanocrystals Confined within Cavities of Hollow Silica Nanoshells: Pt Catalyst-Modified ITO Electrode with Enhanced ECL Performance.

    PubMed

    Cho, Young Shin; Kim, Soo Min; Ju, Youngwon; Kim, Junghoon; Jeon, Ki-Wan; Cho, Seung Hwan; Kim, Joohoon; Lee, In Su

    2017-06-21

    Although the deposition of metallic domains on a preformed semiconductor nanocrystal provides an effective pathway to access diverse hybrid nanocrystals with synergistic metal/semiconductor heterojunction interface, those reactions that take place on the surface of semiconductor nanoscrystals have not been investigated thoroughly, because of the impediments caused by the surface-capping organic surfactants. By exploiting the interfacial reactions occurring between the solution and nanoparticles confined with the cavities of hollow nanoparticles, we propose a novel nanospace-confined strategy for assessing the innate reactivity of surfaces of inorganic semiconductor nanoparticles. This strategy was adopted to investigate the newly discovered process of spontaneous Pt deposition on In2O3 nanocrystals. Through an in-depth examination involving varying key reaction parameters, the Pt deposition process was identified to be templated by the defective In2O3 surface via a unique redox process involving the oxygen vacancies in the In2O3 lattice, whose density can be controlled by high-temperature annealing. The product of the Pt-deposition reaction inside the hollow silica nanoparticle, bearing In2O3-supported Pt catalysts inside the cavity protected by a porous silica shell, was proved to be an effective nanoreactor system which selectively and sustainably catalyzed the reduction reaction of small-sized aromatic nitro-compounds. Moreover, the surfactant-free and electroless Pt deposition protocol, which was devised based on the surface chemistry of the In2O3 nanoparticles, was successfully employed to fabricate Pt-catalyst-modified ITO electrodes with enhanced electrogenerated chemiluminescece (ECL) performance.

  4. Reforming with an improved platinum-containing catalyst

    SciTech Connect

    Pellet, R.J.; Bertolacini, R.J.; Lysholm, D.L.

    1983-08-30

    A catalyst is disclosed which comprises a physical particle-form mixture of a Component A and a Component B. Said Component A comprises one or more Group VIII noble metals and combined halogen deposed on a refractory inorganic oxide and said Component B comprising a metal from Group IVB or Group VB of the Periodic Table of Elements and a combined halogen deposed on a refrac inorganic oxide. Such catalyst is suitable for use in a hydrocarbon conversion reaction zone. The catalyst can be employed in a process for the reforming of a hydrocarbon stream, which process comprises contacting said stream in a reaction zone under reforming conditions and in the presence hydrogen with said catalyst. The catalyst is not presulfided. A preferred process comprises contacting a hydrocarbon stream that contains a substantial amount of sulfur.

  5. Hydroxide catalysts for lignin depolymerization

    DOEpatents

    Beckham, Gregg T.; Biddy, Mary J.; Chmely, Stephen C.; Sturgeon, Matthew

    2017-04-25

    Solid base catalysts and their use for the base-catalyzed depolymerization (BCD) of lignin to compounds such as aromatics are presented herein. Exemplary catalysts include layered double hydroxides (LDHs) as recyclable, heterogeneous catalysts for BCD of lignin.

  6. Peptide-templated noble metal catalysts: syntheses and applications.

    PubMed

    Wang, Wei; Anderson, Caleb F; Wang, Zongyuan; Wu, Wei; Cui, Honggang; Liu, Chang-Jun

    2017-05-01

    Noble metal catalysts have been widely used in many applications because of their high activity and selectivity. However, a controllable preparation of noble metal catalysts still remains as a significant challenge. To overcome this challenge, peptide templates can play a critical role in the controllable syntheses of catalysts owing to their flexible binding with specific metallic surfaces and self-assembly characteristics. By employing peptide templates, the size, shape, facet, structure, and composition of obtained catalysts can all be specifically controlled under the mild synthesis conditions. In addition, catalysts with spherical, nanofiber, and nanofilm structures can all be produced by associating with the self-assembly characteristics of peptide templates. Furthermore, the peptide-templated noble metal catalysts also reveal significantly enhanced catalytic behaviours compared with conventional catalysts because the electron conductivity, metal dispersion, and reactive site exposure can all be improved. In this review, we summarize the research progresses in the syntheses of peptide-templated noble metal catalysts. The applications of the peptide-templated catalysts in organic reactions, photocatalysis, and electrocatalysis are discussed, and the relationship between structure and activity of these catalysts are addressed. Future opportunities, including new catalytic materials designed by using biological principles, are indicated to achieve selective, eco-friendly, and energy neutral synthesis approaches.

  7. Peptide-templated noble metal catalysts: syntheses and applications

    PubMed Central

    Wang, Wei; Anderson, Caleb F.; Wang, Zongyuan; Wu, Wei

    2017-01-01

    Noble metal catalysts have been widely used in many applications because of their high activity and selectivity. However, a controllable preparation of noble metal catalysts still remains as a significant challenge. To overcome this challenge, peptide templates can play a critical role in the controllable syntheses of catalysts owing to their flexible binding with specific metallic surfaces and self-assembly characteristics. By employing peptide templates, the size, shape, facet, structure, and composition of obtained catalysts can all be specifically controlled under the mild synthesis conditions. In addition, catalysts with spherical, nanofiber, and nanofilm structures can all be produced by associating with the self-assembly characteristics of peptide templates. Furthermore, the peptide-templated noble metal catalysts also reveal significantly enhanced catalytic behaviours compared with conventional catalysts because the electron conductivity, metal dispersion, and reactive site exposure can all be improved. In this review, we summarize the research progresses in the syntheses of peptide-templated noble metal catalysts. The applications of the peptide-templated catalysts in organic reactions, photocatalysis, and electrocatalysis are discussed, and the relationship between structure and activity of these catalysts are addressed. Future opportunities, including new catalytic materials designed by using biological principles, are indicated to achieve selective, eco-friendly, and energy neutral synthesis approaches. PMID:28507701

  8. Sulfur sensitivity of Pt/Re catalyst in naphtha reforming

    SciTech Connect

    McClung, R.G.; Oyekan, S.O. )

    1988-01-01

    The role and state of platinum/rhenium in naphtha reforming catalysts have been the subject of substantial research in the last two decades. The role and effect of sulfur has not been studied as extensively especially as it relates to normal onstream operation of a commercial catalytic reformer. This paper presents Pt/Re catalyst performance data showing the effects of feed sulfur on yields and cycle lengths. These laboratory and commercial reformer results are discussed with respect to published fundamental studies results on the state of platinum/rhenium and the effects of sulfur on bimetallic reforming catalyst performance.

  9. Role of dynamics in enzyme catalysis: substantial versus semantic controversies.

    PubMed

    Kohen, Amnon

    2015-02-17

    CONSPECTUS: The role of the enzyme's dynamic motions in catalysis is at the center of heated contemporary debates among both theoreticians and experimentalists. Resolving these apparent disputes is of both intellectual and practical importance: incorporation of enzyme dynamics could be critical for any calculation of enzymatic function and may have profound implications for structure-based drug design and the design of biomimetic catalysts. Analysis of the literature suggests that while part of the dispute may reflect substantial differences between theoretical approaches, much of the debate is semantic. For example, the term "protein dynamics" is often used by some researchers when addressing motions that are in thermal equilibrium with their environment, while other researchers only use this term for nonequilibrium events. The last cases are those in which thermal energy is "stored" in a specific protein mode and "used" for catalysis before it can dissipate to its environment (i.e., "nonstatistical dynamics"). This terminology issue aside, a debate has arisen among theoreticians around the roles of nonstatistical vs statistical dynamics in catalysis. However, the author knows of no experimental findings available today that examined this question in enzyme catalyzed reactions. Another source of perhaps nonsubstantial argument might stem from the varying time scales of enzymatic motions, which range from seconds to femtoseconds. Motions at different time scales play different roles in the many events along the catalytic cascade (reactant binding, reprotonation of reactants, structural rearrangement toward the transition state, product release, etc.). In several cases, when various experimental tools have been used to probe catalytic events at differing time scales, illusory contradictions seem to have emerged. In this Account, recent attempts to sort the merits of those questions are discussed along with possible future directions. A possible summary of current

  10. Nanostructured catalyst supports

    DOEpatents

    Zhu, Yimin; Goldman, Jay L.; Qian, Baixin; Stefan, Ionel C.

    2012-10-02

    The present invention relates to SiC nanostructures, including SiC nanopowder, SiC nanowires, and composites of SiC nanopowder and nanowires, which can be used as catalyst supports in membrane electrode assemblies and in fuel cells. The present invention also relates to composite catalyst supports comprising nanopowder and one or more inorganic nanowires for a membrane electrode assembly.

  11. Nanostructured catalyst supports

    DOEpatents

    Zhu, Yimin; Goldman, Jay L.; Qian, Baixin; Stefan, Ionel C.

    2015-09-29

    The present invention relates to SiC nanostructures, including SiC nanopowder, SiC nanowires, and composites of SiC nanopowder and nanowires, which can be used as catalyst supports in membrane electrode assemblies and in fuel cells. The present invention also relates to composite catalyst supports comprising nanopowder and one or more inorganic nanowires for a membrane electrode assembly.

  12. Fischer-Tropsch Catalysts

    NASA Technical Reports Server (NTRS)

    White, James H. (Inventor); Taylor, Jesse W. (Inventor)

    2008-01-01

    Catalyst compositions and methods for F-T synthesis which exhibit high CO conversion with minor levels (preferably less than 35% and more preferably less than 5%) or no measurable carbon dioxide generation. F-T active catalysts are prepared by reduction of certain oxygen deficient mixed metal oxides.

  13. Decoration of the layered manganese oxide birnessite with Mn(II/III) gives a new water oxidation catalyst with fifty-fold turnover number enhancement.

    PubMed

    McKendry, Ian G; Kondaveeti, Sandeep K; Shumlas, Samantha L; Strongin, Daniel R; Zdilla, Michael J

    2015-08-07

    The role of the manganese average oxidation state (AOS) in water oxidation catalysis by birnessite was investigated. Low AOS samples were most active, generating O2 immediately. Samples with a relatively high AOS showed an initial induction period and decreased turnover. Mn(ii- and iii)-enriched samples gave a 10-50 fold enhancement in turnover number.

  14. 10 CFR 140.84 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 2 2011-01-01 2011-01-01 false Criterion I-Substantial discharge of radioactive material... § 140.84 Criterion I—Substantial discharge of radioactive material or substantial radiation levels... radioactive material offsite, or that there have been substantial levels of radiation offsite, when, as a...

  15. 10 CFR 140.84 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false Criterion I-Substantial discharge of radioactive material... § 140.84 Criterion I—Substantial discharge of radioactive material or substantial radiation levels... radioactive material offsite, or that there have been substantial levels of radiation offsite, when, as a...

  16. 40 CFR 350.27 - Substantiation form to accompany claims of trade secrecy, instructions to substantiation form.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... TRADE SECRET DISCLOSURES TO HEALTH PROFESSIONALS Trade Secrecy Claims § 350.27 Substantiation form to... Secret Substantiation Form General Information EPA requires that the information requested in a trade secret substantiation be completed using this substantiation form in order to ensure that all...

  17. 40 CFR 350.27 - Substantiation form to accompany claims of trade secrecy, instructions to substantiation form.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... TRADE SECRET DISCLOSURES TO HEALTH PROFESSIONALS Trade Secrecy Claims § 350.27 Substantiation form to... Secret Substantiation Form General Information EPA requires that the information requested in a trade secret substantiation be completed using this substantiation form in order to ensure that all...

  18. 40 CFR 350.27 - Substantiation form to accompany claims of trade secrecy, instructions to substantiation form.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... TRADE SECRET DISCLOSURES TO HEALTH PROFESSIONALS Trade Secrecy Claims § 350.27 Substantiation form to... Secret Substantiation Form General Information EPA requires that the information requested in a trade secret substantiation be completed using this substantiation form in order to ensure that all...

  19. 40 CFR 350.27 - Substantiation form to accompany claims of trade secrecy, instructions to substantiation form.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... TRADE SECRET DISCLOSURES TO HEALTH PROFESSIONALS Trade Secrecy Claims § 350.27 Substantiation form to... Secret Substantiation Form General Information EPA requires that the information requested in a trade secret substantiation be completed using this substantiation form in order to ensure that all...

  20. 10 CFR 140.84 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... or substantial radiation levels offsite. 140.84 Section 140.84 Energy NUCLEAR REGULATORY COMMISSION... § 140.84 Criterion I—Substantial discharge of radioactive material or substantial radiation levels... radioactive material offsite, or that there have been substantial levels of radiation offsite, when, as a...

  1. 10 CFR 140.84 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... or substantial radiation levels offsite. 140.84 Section 140.84 Energy NUCLEAR REGULATORY COMMISSION... § 140.84 Criterion I—Substantial discharge of radioactive material or substantial radiation levels... radioactive material offsite, or that there have been substantial levels of radiation offsite, when, as a...

  2. 10 CFR 140.84 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... or substantial radiation levels offsite. 140.84 Section 140.84 Energy NUCLEAR REGULATORY COMMISSION... § 140.84 Criterion I—Substantial discharge of radioactive material or substantial radiation levels... radioactive material offsite, or that there have been substantial levels of radiation offsite, when, as a...

  3. Organometallic polymerization catalysts

    SciTech Connect

    Waymouth, R.M.

    1993-12-31

    Well-defined transition metal catalysts have resulted in exciting new opportunities in polymer synthesis. The stereochemistry of vinyl polymers can be rationally controlled with choice of the appropriate catalysts. Studies with optically active catalyst precursors have revealed considerable information on the absolute stereochemistry of olefin polymerization and have led to the synthesis of novel chiral polyolefins. The development of homogeneous olefin metathesis catalysts has also led to a variety of well-defined new polymer structures with controlled molecular weight and molecular weight distribution. Recent advances in understanding the mechanisms and stereochemistry of homogeneous transition metal catalyzed polymerization will be discussed. The ability to control polymer structure through catalyst design presents exciting opportunities in the synthesis of {open_quotes}tailor-made{close_quotes} macromolecules.

  4. Synthesis and characterization of g-C{sub 3}N{sub 4}/Cu{sub 2}O composite catalyst with enhanced photocatalytic activity under visible light irradiation

    SciTech Connect

    Peng, Biyu; Zhang, Shengsen; Yang, Siyuan; Wang, Hongjuan; Yu, Hao; Zhang, Shanqing; Peng, Feng

    2014-08-15

    The prepared g-C{sub 3}N{sub 4}/Cu{sub 2}O composite exhibited the enhanced photocatalytic activity under visible-light irradiation due to the stronger ability in separation of electron–hole pairs, which was proven by the transient photocurrent measurement. - Highlights: • The coupled Cu{sub 2}O with g-C{sub 3}N{sub 4} of narrow-band-gap semiconductor has been designed. • g-C{sub 3}N{sub 4}/Cu{sub 2}O is prepared via an alcohol-aqueous based on chemical precipitation method. • g-C{sub 3}N{sub 4}/Cu{sub 2}O exhibits the enhanced photocatalytic activity under visible-light. • The enhanced photocatalytic activity is proven by the transient photocurrent test. • A mechanism for the visible-light-driven photocatalysis of g-C{sub 3}N{sub 4}/Cu{sub 2}O is revealed. - Abstract: To overcome the drawback of low photocatalytic efficiency brought by electron–hole pairs recombination and narrow photo-response range, a novel g-C{sub 3}N{sub 4}/Cu{sub 2}O composite photocatalyst was designed and prepared successfully. Compared with bare Cu{sub 2}O and g-C{sub 3}N{sub 4}, the g-C{sub 3}N{sub 4}/Cu{sub 2}O composite exhibited significantly enhanced photocatalytic activity for acid orange-II (AO-II) degradation under visible light irradiation. Based on energy band positions, the mechanism of enhanced visible-light photocatalytic activity was proposed.

  5. Power generation using spinel manganese-cobalt oxide as a cathode catalyst for microbial fuel cell applications.

    PubMed

    Mahmoud, Mohamed; Gad-Allah, Tarek A; El-Khatib, K M; El-Gohary, Fatma

    2011-11-01

    This study focused on the use of spinel manganese-cobalt (Mn-Co) oxide, prepared by a solid state reaction, as a cathode catalyst to replace platinum in microbial fuel cells (MFCs) applications. Spinel Mn-Co oxides, with an Mn/Co atomic ratios of 0.5, 1, and 2, were prepared and examined in an air cathode MFCs which was fed with a molasses-laden synthetic wastewater and operated in batch mode. Among the three Mn-Co oxide cathodes and after 300 h of operation, the Mn-Co oxide catalyst with Mn/Co atomic ratio of 2 (MnCo-2) exhibited the highest power generation 113 mW/m2 at cell potential of 279 mV, which were lower than those for the Pt catalyst (148 mW/m2 and 325 mV, respectively). This study indicated that using spinel Mn-Co oxide to replace platinum as a cathodic catalyst enhances power generation, increases contaminant removal, and substantially reduces the cost of MFCs.

  6. Toward molecular catalysts by computer.

    PubMed

    Raugei, Simone; DuBois, Daniel L; Rousseau, Roger; Chen, Shentan; Ho, Ming-Hsun; Bullock, R Morris; Dupuis, Michel

    2015-02-17

    CONSPECTUS: Rational design of molecular catalysts requires a systematic approach to designing ligands with specific functionality and precisely tailored electronic and steric properties. It then becomes possible to devise computer protocols to design catalysts by computer. In this Account, we first review how thermodynamic properties such as redox potentials (E°), acidity constants (pKa), and hydride donor abilities (ΔGH(-)) form the basis for a framework for the systematic design of molecular catalysts for reactions that are critical for a secure energy future. We illustrate this for hydrogen evolution and oxidation, oxygen reduction, and CO conversion, and we give references to other instances where it has been successfully applied. The framework is amenable to quantum-chemical calculations and conducive to predictions by computer. We review how density functional theory allows the determination and prediction of these thermodynamic properties within an accuracy relevant to experimentalists (∼0.06 eV for redox potentials, ∼1 pKa unit for pKa values, and 1-2 kcal/mol for hydricities). Computation yielded correlations among thermodynamic properties as they reflect the electron population in the d shell of the metal center, thus substantiating empirical correlations used by experimentalists. These correlations point to the key role of redox potentials and other properties (pKa of the parent aminium for the proton-relay-based catalysts designed in our laboratory) that are easily accessible experimentally or computationally in reducing the parameter space for design. These properties suffice to fully determine free energies maps and profiles associated with catalytic cycles, i.e., the relative energies of intermediates. Their prediction puts us in a position to distinguish a priori between desirable and undesirable pathways and mechanisms. Efficient catalysts have flat free energy profiles that avoid high activation barriers due to low- and high

  7. Ferrocene-functionalized graphitic carbon nitride as an enhanced heterogeneous catalyst of Fenton reaction for degradation of Rhodamine B under visible light irradiation.

    PubMed

    Lin, Kun-Yi Andrew; Lin, Jyun-Ting

    2017-09-01

    To enhance degradation of Rhodamine B (RhB), a toxic xanthene dye, an iron-doped graphitic carbon nitride (CN) is prepared by establishing a covalent bond (-CN-) bridging ferrocene (Fc) and CN via a Schiff base reaction. The π-conjugation between the aromatic Fc and CN can be much enhanced by the covalent bond, thereby facilitating the bulk-to-surface charge transfer and separation as well as reversible photo-redox reactions during photocatalytic reactions. Thus, the resulting Fc-CN exhibits a much higher catalytic activity than CN to activate hydrogen peroxide (HP) for RhB degradation, because the photocatalytically generated electrons from CN can activate HP and effectively maintain the bivalence state of Fe in Fc, which also induces the activation of HP. The RhB degradation by the Fc-CN activated HP process (Fc-CN-HP) is validated to involve OH(•) by examining the effect of radical probe agent as well as electron paramagnetic resonance (EPR) spectroscopic analysis. Fc-CN is also proven to activate HP for RhB degradation over multiple times without loss of catalytic activity. Through determining the degradation intermediates, RhB is indeed fully decomposed by Fc-CN-HP into much lower-molecular-weight organic compounds. These features indicate that Fc-functionalization can be an advantageous technique to enhance the catalytic activity of CN for activating HP. The results obtained in this study are essential to further design and utilize Fc-functionalized CN for Fenton-like reactions. The findings shown here, especially the degradation mechanism and pathway, are also quite important for treating xanthene dyes in wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Immobilization of Carbonylcobalt Catalyst by Poly(4-vinylpyridine) (P4VP) through N→Co Coordination Bonds: The Promotional Effect of Pyridine and the Reusability of Polymer Catalyst.

    PubMed

    Liu, Yu-Bing; Wang, Yi-Ning; Lu, Hai-Meng; Liang, Shuang; Xu, Bo-Lian; Fan, Yi-Ning

    2016-11-22

    A carbonylcobalt catalyst, immobilized by poly(4-vinylpyridine) (P4VP) through N→Co coordination bonds, has been prepared by solvothermal method. It has been revealed that the pyridine fragments in the polymer catalyst act not only as promoters to improve the catalytic performance of the carbonylcobalt catalyst for alkoxycarbonylation of ethylene oxide to methyl 3-hydroxypropanoate but also as stabilizers to enhance the reusability of the polymer catalyst. Furthermore, the polymer catalyst could be easily separated by filtration and reused with only a slight loss of catalytic efficiency. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Enhanced stability of CaO and/or La2O3 promoted Pd/Al2O3 egg-shell catalysts in partial oxidation of methane to syngas.

    PubMed

    Wang, Jinlong; Yu, Hongbo; Ma, Zhen; Zhou, Shenghu

    2013-07-15

    An egg-shell Pd/Al2O3 catalyst showed higher activity than a regular Pd/Al2O3 catalyst in the partial oxidation of methane to syngas, but a common problem of this reaction is the catalyst deactivation on stream. We attempted to modify the egg-shell catalyst via impregnation with some metal oxide additives. Although the addition of MgO did not show any beneficial effect, the addition of CaO and/or La2O3 significantly improved the stability due to the suppression of carbon deposition and phase transformation of the Al2O3 support. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, and thermogravimetric analysis (TGA).

  10. Catalyst engineering for lithium ion batteries: the catalytic role of Ge in enhancing the electrochemical performance of SnO2(GeO2)0.13/G anodes.

    PubMed

    Zhu, Yun Guang; Wang, Ye; Han, Zhao Jun; Shi, Yumeng; Wong, Jen It; Huang, Zhi Xiang; Ostrikov, Kostya Ken; Yang, Hui Ying

    2014-12-21

    The catalytic role of germanium (Ge) was investigated to improve the electrochemical performance of tin dioxide grown on graphene (SnO(2)/G) nanocomposites as an anode material of lithium ion batteries (LIBs). Germanium dioxide (GeO(20) and SnO(2) nanoparticles (<10 nm) were uniformly anchored on the graphene sheets via a simple single-step hydrothermal method. The synthesized SnO(2)(GeO(2))0.13/G nanocomposites can deliver a capacity of 1200 mA h g(-1) at a current density of 100 mA g(-1), which is much higher than the traditional theoretical specific capacity of such nanocomposites (∼ 702 mA h g(-1)). More importantly, the SnO(2)(GeO(2))0.13/G nanocomposites exhibited an improved rate, large current capability (885 mA h g(-1) at a discharge current of 2000 mA g(-1)) and excellent long cycling stability (almost 100% retention after 600 cycles). The enhanced electrochemical performance was attributed to the catalytic effect of Ge, which enabled the reversible reaction of metals (Sn and Ge) to metals oxide (SnO(2) and GeO(2)) during the charge/discharge processes. Our demonstrated approach towards nanocomposite catalyst engineering opens new avenues for next-generation high-performance rechargeable Li-ion batteries anode materials.

  11. 20 CFR 220.141 - Substantial gainful activity, defined.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 1 2013-04-01 2012-04-01 true Substantial gainful activity, defined. 220.141 Section 220.141 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT..., defined. Substantial gainful activity is work activity that is both substantial and gainful. (a...

  12. 20 CFR 220.141 - Substantial gainful activity, defined.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 1 2012-04-01 2012-04-01 false Substantial gainful activity, defined. 220.141 Section 220.141 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD..., defined. Substantial gainful activity is work activity that is both substantial and gainful. (a...

  13. 20 CFR 220.141 - Substantial gainful activity, defined.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 1 2011-04-01 2011-04-01 false Substantial gainful activity, defined. 220.141 Section 220.141 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD..., defined. Substantial gainful activity is work activity that is both substantial and gainful. (a...

  14. 24 CFR 907.3 - Bases for substantial default.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 24 Housing and Urban Development 4 2013-04-01 2013-04-01 false Bases for substantial default. 907.3 Section 907.3 Housing and Urban Development REGULATIONS RELATING TO HOUSING AND URBAN DEVELOPMENT... DEVELOPMENT SUBSTANTIAL DEFAULT BY A PUBLIC HOUSING AGENCY § 907.3 Bases for substantial default....

  15. 24 CFR 907.3 - Bases for substantial default.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 4 2011-04-01 2011-04-01 false Bases for substantial default. 907.3 Section 907.3 Housing and Urban Development REGULATIONS RELATING TO HOUSING AND URBAN DEVELOPMENT... DEVELOPMENT SUBSTANTIAL DEFAULT BY A PUBLIC HOUSING AGENCY § 907.3 Bases for substantial default....

  16. 24 CFR 907.3 - Bases for substantial default.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 24 Housing and Urban Development 4 2012-04-01 2012-04-01 false Bases for substantial default. 907.3 Section 907.3 Housing and Urban Development REGULATIONS RELATING TO HOUSING AND URBAN DEVELOPMENT... DEVELOPMENT SUBSTANTIAL DEFAULT BY A PUBLIC HOUSING AGENCY § 907.3 Bases for substantial default....

  17. 24 CFR 907.3 - Bases for substantial default.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 4 2014-04-01 2014-04-01 false Bases for substantial default. 907.3 Section 907.3 Housing and Urban Development REGULATIONS RELATING TO HOUSING AND URBAN DEVELOPMENT... DEVELOPMENT SUBSTANTIAL DEFAULT BY A PUBLIC HOUSING AGENCY § 907.3 Bases for substantial default....

  18. 19 CFR 10.7 - Substantial containers or holders.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Substantial containers or holders. 10.7 Section 10... Exported and Returned § 10.7 Substantial containers or holders. (a) Substantial containers or holders... domestic products exported and returned. When such containers or holders are imported not containing...

  19. 29 CFR 825.218 - Substantial and grievous economic injury.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 3 2011-07-01 2011-07-01 false Substantial and grievous economic injury. 825.218 Section... Medical Leave Act § 825.218 Substantial and grievous economic injury. (a) In order to deny restoration to... cause “substantial and grievous economic injury” to the operations of the employer, not whether the...

  20. 29 CFR 825.218 - Substantial and grievous economic injury.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Substantial and grievous economic injury. 825.218 Section... Medical Leave Act § 825.218 Substantial and grievous economic injury. (a) In order to deny restoration to... cause “substantial and grievous economic injury” to the operations of the employer, not whether the...

  1. Low energy electron catalyst: the electronic origin of catalytic strategies.

    PubMed

    Davis, Daly; Sajeev, Y

    2016-10-12

    Using a low energy electron (LEE) as a catalyst, the electronic origin of the catalytic strategies corresponding to substrate selectivity, reaction specificity and reaction rate enhancement is investigated for a reversible unimolecular elementary reaction. An electronic energy complementarity between the catalyst and the substrate molecule is the origin of substrate selectivity and reaction specificity. The electronic energy complementarity is induced by tuning the electronic energy of the catalyst. The energy complementarity maximizes the binding forces between the catalyst and the molecule. Consequently, a new electronically metastable high-energy reactant state and a corresponding new low barrier reaction path are resonantly created for a specific reaction of the substrate through the formation of a catalyst-substrate transient adduct. The LEE catalysis also reveals a fundamental structure-energy correspondence in the formation of the catalyst-substrate transient adduct. Since the energy complementarities corresponding to the substrate molecules of the forward and the backward steps of the reversible reactions are not the same due to their structural differences, the LEE catalyst exhibits a unique one-way catalytic strategy, i.e., the LEE catalyst favors the reversible reaction more effectively in one direction. A characteristic stronger binding of the catalyst to the transition state of the reaction than in the initial reactant state and the final product state is the molecular origin of barrier lowering.

  2. A novel multiple signal amplifying immunosensor based on the strategy of in situ-produced electroactive substance by ALP and carbon-based Ag-Au bimetallic as the catalyst and signal enhancer.

    PubMed

    Zhang, Si; Li, Renkai; Liu, Xiaoying; Yang, Liuqing; Lu, Qiujun; Liu, Meiling; Li, Haitao; Zhang, Youyu; Yao, Shouzhuo

    2017-06-15

    In this work, a novel immunosensor was constructed based on the alkaline phosphatase (ALP) in situ generating an electroactive substance by enzymatic hydrolysis the inactive substrates. The new signal-amplified strategy for sensitive detection of HIgG was based on the catalytic oxidation of ALP-generated products, ascorbic acid (AA), using carbon-based Ag-Au bimetallic as the catalyst and signal enhancer. Through a sandwich reaction, ALP-Ab2 bioconjugates were captured on the electrode surface and the amplified signal can be obtained as follows: the ALP catalyzed the inactive substrate L-ascorbic acid 2-phosphate (AAP) to in situ produce AA; AA as an electroactive product then can be directly electro-oxidized to generate electrochemical signal; At the same time, AA could be catalytic oxidized by Ag-Au bimetallic and resulted in the amplification of electrochemical signal; Finally, the oxidation of Ag on the Ag-Au bimetallic maybe further enhance the detection signal. The proposed immunosensor achieved good linear in the range of 0.005-100ngmL(-1) with the detection limit of 0.0009ngmL(-1) (S/N =3). The proposed immunosensor was successfully applied in the analysis of human IgG in real samples and got satisfied results. The present work demonstrates a general strategy for the design of multifunctional nanomaterials based on carbon-based bimetallic nanoparticles for different applications, such as biosensors, immunosensors and nanocatalysts. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Methane activation on supported transition metal catalysts

    NASA Astrophysics Data System (ADS)

    Carstens, Jason Ned

    that partial reduction of PdO with methane leads to a catalyst that is able to activate methane more readily than a catalyst that has been partially reduced with hydrogen. This suggests that reduced metal is important in activating methane. In the second part of the study, the methane combustion activity of the catalyst was examined on partially oxidized and partially reduced catalysts. Observations suggest that the presence of Pd may enhance methane combustion activity, but only until the Pd is oxidized. (Abstract shortened by UMI.)

  4. Fuel cell development for transportation: Catalyst development

    SciTech Connect

    Doddapaneni, N.; Ingersoll, D.

    1996-12-31

    Fuel cells are being considered as alternative power sources for transportation and stationary applications. The degradation of commonly used electrode catalysts (e.g. Pt, Ag, and others) and corrosion of carbon substrates are making commercialization of fuel cells incorporating present day technologies economically problematic. Furthermore, due to the instability of the Pt catalyst, the performance of fuel cells declines on long-term operation. When methanol is used as the fuel, a voltage drop, as well as significant thermal management problems can be encountered, the later being due to chemical oxidation of methanol at the platinized carbon at the cathode. Though extensive work was conducted on platinized electrodes for both the oxidation and reduction reactions, due to the problems mentioned above, fuel cells have not been fully developed for widespread commercial use. Several investigators have previously evaluated metal macrocyclic complexes as alternative catalysts to Pt and Pt/Ru in fuel cells. Unfortunately, though they have demonstrated catalytic activity, these materials were found to be unstable on long term use in the fuel cell environment. In order to improve the long-term stability of metal macrocyclic complexes, we have chemically bonded these complexes to the carbon substrate, thereby enhancing their catalytic activity as well as their chemical stability in the fuel cell environment. We have designed, synthesized, and evaluated these catalysts for O{sub 2} reduction, H{sub 2} oxidation, and direct methanol oxidation in Proton Exchange Membrane (PEM) and aqueous carbonate fuel cells. These catalysts exhibited good catalytic activity and long-term stability. In this paper we confine our discussion to the initial performance results of some of these catalysts in H{sub 2}/O{sub 2} PEM fuel cells, including their long-term performance characteristics as well as CO poisoning effects on these catalysts.

  5. Catalytic reforming with improved zeolite catalysts

    SciTech Connect

    Chu, Y.F.

    1990-05-22

    This patent describes a method for reforming a naphtha. It comprises contacting the naphtha with a noble metal/alkali metal-containing zeolite naphtha reforming catalyst the catalyst containing from about 0.1--1.0 wt % of the noble metal and an amount of the alkali metal which exceeds the cationic exchange capacity of the zeolite, a pressure of from about 0 to about 2000 psig, a temperature of about 750{degrees} F. to about 1200{degrees} F., a hydrogen to hydrocarbon molar ratio of about 0.1 to 1 to about 15 to 1 and a weight hourly spaced velocity of about 0.5 to about 20, whereby naphtha reforming activity of the catalyst is enhanced by the zeolite resulting in significantly improved C{sub 4}{sup +} gasoline yields.

  6. Pyrochlore catalysts for hydrocarbon fuel reforming

    DOEpatents

    Berry, David A.; Shekhawat, Dushyant; Haynes, Daniel; Smith, Mark; Spivey, James J.

    2012-08-14

    A method of catalytically reforming a reactant gas mixture using a pyrochlore catalyst material comprised of one or more pyrochlores having the composition A2B2-y-zB'yB"zO7-.DELTA., where y>0 and z.gtoreq.0. Distribution of catalytically active metals throughout the structure at the B site creates an active and well dispersed metal locked into place in the crystal structure. This greatly reduces the metal sintering that typically occurs on supported catalysts used in reforming reactions, and reduces deactivation by sulfur and carbon. Further, oxygen mobility may also be enhanced by elemental exchange of promoters at sites in the pyrochlore. The pyrochlore catalyst material may be utilized in catalytic reforming reactions for the conversion of hydrocarbon fuels into synthesis gas (H2+CO) for fuel cells, among other uses.

  7. Protein Scaffolding for Small Molecule Catalysts

    SciTech Connect

    Baker, David

    2014-09-14

    We aim to design hybrid catalysts for energy production and storage that combine the high specificity, affinity, and tunability of proteins with the potent chemical reactivities of small organometallic molecules. The widely used Rosetta and RosettaDesign methodologies will be extended to model novel protein / small molecule catalysts in which one or many small molecule active centers are supported and coordinated by protein scaffolding. The promise of such hybrid molecular systems will be demonstrated with the nickel-phosphine hydrogenase of DuBois et. al.We will enhance the hydrogenase activity of the catalyst by designing protein scaffolds that incorporate proton relays and systematically modulate the local environment of the catalyticcenter. In collaboration with DuBois and Shaw, the designs will be experimentally synthesized and characterized.

  8. Catalyst for microelectromechanical systems microreactors

    DOEpatents

    Morse, Jeffrey D [Martinez, CA; Sopchak, David A [Livermore, CA; Upadhye, Ravindra S [Pleasanton, CA; Reynolds, John G [San Ramon, CA; Satcher, Joseph H [Patterson, CA; Gash, Alex E [Brentwood, CA

    2011-11-15

    A microreactor comprising a silicon wafer, a multiplicity of microchannels in the silicon wafer, and a catalyst coating the microchannels. In one embodiment the catalyst coating the microchannels comprises a nanostructured material. In another embodiment the catalyst coating the microchannels comprises an aerogel. In another embodiment the catalyst coating the microchannels comprises a solgel. In another embodiment the catalyst coating the microchannels comprises carbon nanotubes.

  9. Catalyst for microelectromechanical systems microreactors

    DOEpatents

    Morse, Jeffrey D [Martinez, CA; Sopchak, David A [Livermore, CA; Upadhye, Ravindra S [Pleasanton, CA; Reynolds, John G [San Ramon, CA; Satcher, Joseph H [Patterson, CA; Gash, Alex E [Brentwood, CA

    2010-06-29

    A microreactor comprising a silicon wafer, a multiplicity of microchannels in the silicon wafer, and a catalyst coating the microchannels. In one embodiment the catalyst coating the microchannels comprises a nanostructured material. In another embodiment the catalyst coating the microchannels comprises an aerogel. In another embodiment the catalyst coating the microchannels comprises a solgel. In another embodiment the catalyst coating the microchannels comprises carbon nanotubes.

  10. Enhanced catalyst-free nucleation of GaN nanowires on amorphous Al{sub 2}O{sub 3} by plasma-assisted molecular beam epitaxy

    SciTech Connect

    Sobanska, Marta Klosek, Kamil; Borysiuk, Jolanta; Kret, Slawomir; Tchutchulasvili, Giorgi; Gieraltowska, Sylwia; Zytkiewicz, Zbigniew R.

    2014-01-28

    We report on plasma-assisted molecular beam epitaxial growth of GaN nanowires (NWs) on Si(111) substrates with a thin amorphous Al{sub 2}O{sub 3} buffer layer deposited by atomic layer deposition. Comparison of nucleation kinetics shows that presence of amorphous Al{sub 2}O{sub 3} buffer significantly enhances spontaneous nucleation of GaN NWs. Slower nucleation was observed on partially amorphous silicon nitride films. No growth of NWs was found on sapphire substrate under the same growth conditions which we explain by a low density of defects on monocrystalline substrate surface where NWs may nucleate. Our finding shows that tuning of substrate microstructure is an efficient tool to control rate of self-induced nucleation of GaN NWs.

  11. Catalysts and method

    DOEpatents

    Taylor, Charles E.; Noceti, Richard P.

    1991-01-01

    An improved catlayst and method for the oxyhydrochlorination of methane is disclosed. The catalyst includes a pyrogenic porous support on which is layered as active material, cobalt chloride in major proportion, and minor proportions of an alkali metal chloride and of a rare earth chloride. On contact of the catalyst with a gas flow of methane, HC1 and oxygen, more than 60% of the methane is converted and of that converted more than 40% occurs as monochloromethane. Advantageously, the monochloromethane can be used to produce gasoline boiling range hydrocarbons with the recycle of HCl for further reaction. This catalyst is also of value for the production of formic acid as are analogous catalysts with lead, silver or nickel chlorides substituted for the cobalt chloride.

  12. Reclaim spent catalysts properly

    SciTech Connect

    Lassner, J.A.; Lasher, L.B.; Koppel, R.L.; Hamilton, J.N.

    1994-08-01

    Treatment of spent catalysts and metallic by products has become increasingly more complex over the last couple of years, due to tightening environmental concerns. Three options are available: (1) Reclaiming the metals and either reusing them to make new catalyst or recycling them for other uses. This is now the preferred option. A reclaiming firm is generally employed to handle the task. (2) Regeneration and reuse. While this generally is the preferred option, few commercial catalysts can be regenerated effectively and economically. (3) Landfilling. This has been the traditional route. However, stricter environmental regulations have made landfilling unattractive. To maximize the reclamation both economically and environmentally, five factors should be addressed: (1) proper planning and physical handling; (2) transportation of materials; (3) environmental concerns; (4) end uses of the catalyst; and (5) choosing the proper reclamation partner. These factors are discussed.

  13. Catalytic reforming catalyst

    SciTech Connect

    Buss, W.C.; Kluksdahl, H.E.

    1980-12-09

    An improved catalyst, having a reduced fouling rate when used in a catalytic reforming process, said catalyst comprising platinum disposed on an alumina support wherein the alumina support is obtained by removing water from aluminum hydroxide produced as a by-product from a ziegler higher alcohol synthesis reaction, and wherein the alumina is calcined at a temperature of 1100-1400/sup 0/F so as to have a surface area of 165 to 215 square meters per gram.

  14. Plasmatron-catalyst system

    SciTech Connect

    Bromberg, Leslie; Cohn, Daniel R.; Rabinovich, Alexander; Alexeev, Nikolai

    2007-10-09

    A plasmatron-catalyst system. The system generates hydrogen-rich gas and comprises a plasmatron and at least one catalyst for receiving an output from the plasmatron to produce hydrogen-rich gas. In a preferred embodiment, the plasmatron receives as an input air, fuel and water/steam for use in the reforming process. The system increases the hydrogen yield and decreases the amount of carbon monoxide.

  15. Plasmatron-catalyst system

    DOEpatents

    Bromberg, Leslie; Cohn, Daniel R.; Rabinovich, Alexander; Alexeev, Nikolai

    2004-09-21

    A plasmatron-catalyst system. The system generates hydrogen-rich gas and comprises a plasmatron and at least one catalyst for receiving an output from the plasmatron to produce hydrogen-rich gas. In a preferred embodiment, the plasmatron receives as an input air, fuel and water/steam for use in the reforming process. The system increases the hydrogen yield and decreases the amount of carbon monoxide.

  16. 10 CFR 840.4 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Criterion I-Substantial discharge of radioactive material... EXTRAORDINARY NUCLEAR OCCURRENCES § 840.4 Criterion I—Substantial discharge of radioactive material or... dispersal of radioactive material offsite, or that there have been substantial levels of radiation offsite...

  17. 10 CFR 840.4 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 4 2014-01-01 2014-01-01 false Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite. 840.4 Section 840.4 Energy DEPARTMENT OF ENERGY EXTRAORDINARY NUCLEAR OCCURRENCES § 840.4 Criterion I—Substantial discharge of radioactive material...

  18. 10 CFR 840.4 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 4 2012-01-01 2012-01-01 false Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite. 840.4 Section 840.4 Energy DEPARTMENT OF ENERGY EXTRAORDINARY NUCLEAR OCCURRENCES § 840.4 Criterion I—Substantial discharge of radioactive material...

  19. 10 CFR 840.4 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 4 2013-01-01 2013-01-01 false Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite. 840.4 Section 840.4 Energy DEPARTMENT OF ENERGY EXTRAORDINARY NUCLEAR OCCURRENCES § 840.4 Criterion I—Substantial discharge of radioactive material...

  20. 10 CFR 840.4 - Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Criterion I-Substantial discharge of radioactive material or substantial radiation levels offsite. 840.4 Section 840.4 Energy DEPARTMENT OF ENERGY EXTRAORDINARY NUCLEAR OCCURRENCES § 840.4 Criterion I—Substantial discharge of radioactive material...

  1. Catalyst system comprising a first catalyst system tethered to a supported catalyst

    DOEpatents

    Angelici, Robert J.; Gao, Hanrong

    1998-08-04

    The present invention provides new catalyst formats which comprise a supported catalyst tethered to a second and different catalyst by a suitable tethering ligand. A preferred system comprises a heterogeneous supported metal catalyst tethered to a homogeneous catalyst. This combination of homogeneous and heterogeneous catalysts has a sufficient lifetime and unusually high catalytic activity in arene hydrogenations, and potentially many other reactions as well, including, but not limited to hydroformylation, hydrosilation, olefin oxidation, isomerization, hydrocyanation, olefin metathesis, olefin polymerization, carbonylation, enantioselective catalysis and photoduplication. These catalysts are easily separated from the products, and can be reused repeatedly, making these systems very economical.

  2. Catalyst system comprising a first catalyst system tethered to a supported catalyst

    DOEpatents

    Angelici, R.J.; Gao, H.

    1998-08-04

    The present invention provides new catalyst formats which comprise a supported catalyst tethered to a second and different catalyst by a suitable tethering ligand. A preferred system comprises a heterogeneous supported metal catalyst tethered to a homogeneous catalyst. This combination of homogeneous and heterogeneous catalysts has a sufficient lifetime and unusually high catalytic activity in arene hydrogenations, and potentially many other reactions as well, including, but not limited to hydroformylation, hydrosilication, olefin oxidation, isomerization, hydrocyanidation, olefin metathesis, olefin polymerization, carbonylation, enantioselective catalysis and photoduplication. These catalysts are easily separated from the products, and can be reused repeatedly, making these systems very economical. 2 figs.

  3. Substantial overnight reaeration by convective cooling discovered in pond ecosystems

    NASA Astrophysics Data System (ADS)

    Holgerson, Meredith A.; Zappa, Christopher J.; Raymond, Peter A.

    2016-08-01

    Trends in freshwater dissolved oxygen (DO) reflect whole-ecosystem properties and influence organismal survival and behavior. Here we show that small ponds have unique oxygen dynamics that differ from larger lakes. We discovered that ponds undersaturated in DO experienced substantial increases in oxygen concentration overnight. Nighttime increases in DO occurred on 45% of the nights sampled and resulted in DO saturation increasing 12-fold (22% saturation) on average. Oxygen spikes were likely to occur when ponds became at least 1.8°C warmer than the air and later in the season when oxygen levels were low (<31% saturation) and the air was warm (≥5.8°C). We demonstrate that overnight increases in surface water DO resulted from atmospheric oxygen invasion as opposed to internal production. Convective cooling enhanced turbulence and air-water gas exchange, leading to intense bursts of oxygen invasion during nighttime hours. This mechanism has not been demonstrated before and has important implications for the biogeochemistry of these systems, as well as understanding how organisms survive in hypoxic small ponds.

  4. Enhanced heterologous expression of two Streptomyces griseolus cytochrome P450s and Streptomyces coelicolor ferredoxin reductase as potentially efficient hydroxylation catalysts.

    PubMed

    Hussain, Haitham A; Ward, John M

    2003-01-01

    The herbicide-inducible, soluble cytochrome P450s CYP105A1 and CYP105B1 and their adjacent ferredoxins, Fd1 and Fd2, of Streptomyces griseolus were expressed in Escherichia coli to high levels. Conditions for high-level expression of active enzyme able to catalyze hydroxylation have been developed. Analysis of the expression levels of the P450 proteins in several different E. coli expression hosts identified E. coli BL21 Star(DE3)pLysS as the optimal host cell to express CYP105B1 as judged by CO difference spectra. Examination of the codons used in the CYP1051A1 sequence indicated that it contains a number of codons corresponding to rare E. coli tRNA species. The level of its expression was improved in the modified forms of E. coli BL21(DE3), which contain extra copies of rare codon E. coli tRNA genes. The activity of correctly folded cytochrome P450s was further enhanced by cloning a ferredoxin reductase from Streptomyces coelicolor downstream of CYP105A1 and CYP105B1 and their adjacent ferredoxins. Expression of CYP105A1 and CYP105B1 was also achieved in Streptomyces lividans 1326 by cloning the P450 genes and their ferredoxins into the expression vector pBW160. S. lividans 1326 cells containing CYP105A1 or CYP105B1 were able efficiently to dealkylate 7-ethoxycoumarin.

  5. Magnetic and dendritic catalysts.

    PubMed

    Wang, Dong; Deraedt, Christophe; Ruiz, Jaime; Astruc, Didier

    2015-07-21

    The recovery and reuse of catalysts is a major challenge in the development of sustainable chemical processes. Two methods at the frontier between homogeneous and heterogeneous catalysis have recently emerged for addressing this problem: loading the catalyst onto a dendrimer or onto a magnetic nanoparticle. In this Account, we describe representative examples of these two methods, primarily from our research group, and compare them. We then describe new chemistry that combines the benefits of these two methods of catalysis. Classic dendritic catalysis has involved either attaching the catalyst covalently at the branch termini or within the dendrimer core. We have used chelating pyridyltriazole ligands to insolubilize catalysts at the termini of dendrimers, providing an efficient, recyclable heterogeneous catalysts. With the addition of dendritic unimolecular micelles olefin metathesis reactions catalyzed by commercial Grubbs-type ruthenium-benzylidene complexes in water required unusually low amounts of catalyst. When such dendritic micelles include intradendritic ligands, both the micellar effect and ligand acceleration promote faster catalysis in water. With these types of catalysts, we could carry out azide alkyne cycloaddition ("click") chemistry with only ppm amounts of CuSO4·5H2O and sodium ascorbate under ambient conditions. Alternatively we can attach catalysts to the surface of superparamagnetic iron oxide nanoparticles (SPIONs), essentially magnetite (Fe3O4) or maghemite (γ-Fe2O3), offering the opportunity to recover the catalysts using magnets. Taking advantage of the merits of both of these strategies, we and others have developed a new generation of recyclable catalysts: dendritic magnetically recoverable catalysts. In particular, some of our catalysts with a γ-Fe2O3@SiO2 core and 1,2,3-triazole tethers and loaded with Pd nanoparticles generate strong positive dendritic effects with respect to ligand loading, catalyst loading, catalytic activity and

  6. Oxidation-reduction catalyst and its process of use

    NASA Technical Reports Server (NTRS)

    Jordan, Jeffrey D. (Inventor); Watkins, Anthony Neal (Inventor); Schryer, Jacqueline L. (Inventor); Oglesby, Donald M. (Inventor)

    2008-01-01

    This invention relates generally to a ruthenium stabilized oxidation-reduction catalyst useful for oxidizing carbon monoxide, and volatile organic compounds, and reducing nitrogen oxide species in oxidizing environments, substantially without the formation of toxic and volatile ruthenium oxide species upon said oxidizing environment being at high temperatures.

  7. Supported Molten Metal Catalysis. A New Class of Catalysts

    SciTech Connect

    Ravindra Datta; Ajeet Singh; Manuela Serban; Istvan Halasz

    2006-06-02

    We describe a new class of heterogeneous catalysts called supported molten metal catalysis (SMMC), in which molten metal catalysts are dispersed as nanodroplets on the surface of porous supports, allowing much larger active surface area than is possible in conventional contacting techniques for catalytic metals that are molten under reaction conditions, thus greatly enhancing their activity and potential utility. Specific examples of different types of reactions are provided to demonstrate the broad applicability of the technique in designing active, selective, and stable new catalysts. It is shown that dispersing the molten metal on a support in the suggested manner can enhance the rate of a reaction by three to four orders of magnitude as a result of the concomitant increase in the active surface area. New reaction examples include {gamma}-Al{sub 2}O{sub 3} supported molten Te (melting point 450 C) and Ga (MP 30 C) catalysts for bifunctional methylcyclohexane dehydrogenation. These catalysts provide activity similar to conventional Pt-based catalysts for this with better resistance to coking. In addition, results are described for a controlled pore glass supported molten In (MP 157 C) catalyst for the selective catalytic reduction of NO with ethanol in the presence of water, demonstrating activities superior to conventional catalysts for this reaction. A discussion is also provided on the characterization of the active surface area and dispersion of these novel supported catalysts. It is clear based on the results described that the development of new active and selective supported molten metal catalysts for practical applications is entirely plausible.

  8. The Constitution of the Human Embryo as Substantial Change

    PubMed Central

    Alvargonzález, David

    2016-01-01

    This paper analyzes the transformation from the human zygote to the implanted embryo under the prism of substantial change. After a brief introduction, it vindicates the Aristotelian ideas of substance and accident, and those of substantial and accidental change. It then claims that the transformation from the multicelled zygote to the implanted embryo amounts to a substantial change. Pushing further, it contends that this substantial change cannot be explained following patterns of genetic reductionism, emergence, and self-organization, and proposes Gustavo Bueno’s idea of anamorphosis as a means to encapsulate criticism against such positions. PMID:26850033

  9. Catalyst engineering for lithium ion batteries: the catalytic role of Ge in enhancing the electrochemical performance of SnO2(GeO2)0.13/G anodes

    NASA Astrophysics Data System (ADS)

    Zhu, Yun Guang; Wang, Ye; Han, Zhao Jun; Shi, Yumeng; Wong, Jen It; Huang, Zhi Xiang; Ostrikov, Kostya Ken; Yang, Hui Ying

    2014-11-01

    The catalytic role of germanium (Ge) was investigated to improve the electrochemical performance of tin dioxide grown on graphene (SnO2/G) nanocomposites as an anode material of lithium ion batteries (LIBs). Germanium dioxide (GeO2) and SnO2 nanoparticles (<10 nm) were uniformly anchored on the graphene sheets via a simple single-step hydrothermal method. The synthesized SnO2(GeO2)0.13/G nanocomposites can deliver a capacity of 1200 mA h g-1 at a current density of 100 mA g-1, which is much higher than the traditional theoretical specific capacity of such nanocomposites (~702 mA h g-1). More importantly, the SnO2(GeO2)0.13/G nanocomposites exhibited an improved rate, large current capability (885 mA h g-1 at a discharge current of 2000 mA g-1) and excellent long cycling stability (almost 100% retention after 600 cycles). The enhanced electrochemical performance was attributed to the catalytic effect of Ge, which enabled the reversible reaction of metals (Sn and Ge) to metals oxide (SnO2 and GeO2) during the charge/discharge processes. Our demonstrated approach towards nanocomposite catalyst engineering opens new avenues for next-generation high-performance rechargeable Li-ion batteries anode materials.The catalytic role of germanium (Ge) was investigated to improve the electrochemical performance of tin dioxide grown on graphene (SnO2/G) nanocomposites as an anode material of lithium ion batteries (LIBs). Germanium dioxide (GeO2) and SnO2 nanoparticles (<10 nm) were uniformly anchored on the graphene sheets via a simple single-step hydrothermal method. The synthesized SnO2(GeO2)0.13/G nanocomposites can deliver a capacity of 1200 mA h g-1 at a current density of 100 mA g-1, which is much higher than the traditional theoretical specific capacity of such nanocomposites (~702 mA h g-1). More importantly, the SnO2(GeO2)0.13/G nanocomposites exhibited an improved rate, large current capability (885 mA h g-1 at a discharge current of 2000 mA g-1) and excellent long

  10. Characterisation of gold catalysts.

    PubMed

    Villa, Alberto; Dimitratos, Nikolaos; Chan-Thaw, Carine E; Hammond, Ceri; Veith, Gabriel M; Wang, Di; Manzoli, Maela; Prati, Laura; Hutchings, Graham J

    2016-09-21

    Au-based catalysts have established a new important field of catalysis, revealing specific properties in terms of both high activity and selectivity for many reactions. However, the correlation between the morphology and the activity of the catalyst is not always clear although much effort has been addressed to this task. To some extent the problem relates to the complexity of the characterisation techniques that can be applied to Au catalyst and the broad range of ways in which they can be prepared. Indeed, in many reports only a few characterization techniques have been used to investigate the potential nature of the active sites. The aim of this review is to provide a critical description of the techniques that are most commonly used as well as the more advanced characterization techniques available for this task. The techniques that we discuss are (i) transmission electron microscopy methods, (ii) X-ray spectroscopy techniques, (iii) vibrational spectroscopy techniques and (iv) chemisorption methods. The description is coupled with developing an understanding of a number of preparation methods. In the final section the example of the supported AuPd alloy catalyst is discussed to show how the techniques can gain an understanding of an active oxidation catalyst.

  11. Highly efficient molybdenum-based catalysts for enantioselective alkene metathesis

    PubMed Central

    Malcolmson, Steven J.; Meek, Simon J.; Sattely, Elizabeth S.; Schrock, Richard R.; Hoveyda, Amir H.

    2009-01-01

    Discovery of efficient catalysts is one of the most compelling objectives of modern chemistry. Chiral catalysts are in particularly high demand, as they facilitate synthesis of enantiomerically enriched small molecules that are critical to developments in medicine, biology and materials science1. Especially noteworthy are catalysts that promote—with otherwise inaccessible efficiency and selectivity levels—reactions demonstrated to be of great utility in chemical synthesis. Here we report a class of chiral catalysts that initiate alkene metathesis1 with very high efficiency and enantioselectivity. Such attributes arise from structural fluxionality of the chiral catalysts and the central role that enhanced electronic factors have in the catalytic cycle. The new catalysts have a stereogenic metal centre and carry only monodentate ligands; the molybdenum-based complexes are prepared stereoselectively by a ligand exchange process involving an enantiomerically pure aryloxide, a class of ligands scarcely used in enantioselective catalysis2,3. We demonstrate the application of the new catalysts in an enantioselective synthesis of the Aspidosperma alkaloid, quebrachamine, through an alkene metathesis reaction that cannot be promoted by any of the previously reported chiral catalysts. PMID:19011612

  12. Child protection decisions to substantiate hospital child protection teams' reports of suspected maltreatment.

    PubMed

    Jedwab, Merav; Benbenishty, Rami; Chen, Wendy; Glasser, Saralee; Siegal, Gil; Lerner-Geva, Liat

    2015-02-01

    The present study focuses on the way child protection officers (CPOs) in Israel assess suspected abuse and neglect (SCAN) reports made by hospital child protection teams (CPTs), to determine whether the alleged maltreatment is substantiated. The study was conducted in six medical centers and included 358 reports investigated by CPOs for SCAN. A structured questionnaire was completed by hospital CPTs to capture all relevant information on each child referred to the CPTs. Structured phone interviews were conducted with each of the CPOs who received a CPT report. Bivariate associations and multivariate logistic regressions were conducted to estimate the substantiation rate of cases reported by CPTs and the types of maltreatment substantiated, as well as to identify case characteristics of the child and the family that were associated with the CPOs' substantiation decision. CPO follow-up investigations revealed a substantiation rate of 53.5%. The maltreatment type most commonly substantiated was neglect. The case characteristics associated with substantiation included socio-demographic background, parents' health and functioning, previous contact with social services, characteristics of the hospital referral, medical findings and an assessment of the parents' behaviors. The findings of the study highlighted the importance of cooperation between the health and welfare services and the policy makers. This cooperation is essential for identifying early signs of maltreatment. Enhanced cooperation and effective information transfer between various professionals would help prevent or at least reduce the recurrence of maltreatment and would ensure that the children and their families are treated appropriately.

  13. Supported organoiridium catalysts for alkane dehydrogenation

    SciTech Connect

    Baker, R. Thomas; Sattelberger, Alfred P.; Li, Hongbo

    2013-09-03

    Solid supported organoiridium catalysts, a process for preparing such solid supported organoiridium catalysts, and the use of such solid supported organoiridium catalysts in dehydrogenation reactions of alkanes is provided. The catalysts can be easily recovered and recycled.

  14. Self-optimizing, highly surface-active layered metal dichalcogenide catalysts for hydrogen evolution

    NASA Astrophysics Data System (ADS)

    Liu, Yuanyue; Wu, Jingjie; Hackenberg, Ken P.; Zhang, Jing; Wang, Y. Morris; Yang, Yingchao; Keyshar, Kunttal; Gu, Jing; Ogitsu, Tadashi; Vajtai, Robert; Lou, Jun; Ajayan, Pulickel M.; Wood, Brandon C.; Yakobson, Boris I.

    2017-09-01

    Low-cost, layered transition-metal dichalcogenides (MX2) based on molybdenum and tungsten have attracted substantial interest as alternative catalysts for the hydrogen evolution reaction (HER). These materials have high intrinsic per-site HER activity; however, a significant challenge is the limited density of active sites, which are concentrated at the layer edges. Here we unravel electronic factors underlying catalytic activity on MX2 surfaces, and leverage the understanding to report group-5 MX2 (H-TaS2 and H-NbS2) electrocatalysts whose performance instead mainly derives from highly active basal-plane sites, as suggested by our first-principles calculations and performance comparisons with edge-active counterparts. Beyond high catalytic activity, they are found to exhibit an unusual ability to optimize their morphology for enhanced charge transfer and accessibility of active sites as the HER proceeds, offering a practical advantage for scalable processing. The catalysts reach 10 mA cm‑2 current density at an overpotential of ∼50-60 mV with a loading of 10-55 μg cm‑2, surpassing other reported MX2 candidates without any performance-enhancing additives.

  15. 20 CFR 604.6 - Conformity and substantial compliance.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Conformity and substantial compliance. 604.6... FOR ELIGIBILITY FOR UNEMPLOYMENT COMPENSATION § 604.6 Conformity and substantial compliance. (a) In... for the administration of its UC program. (b) Resolving Issues of Conformity and...

  16. 26 CFR 1.528-4 - Substantiality test.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 7 2014-04-01 2013-04-01 true Substantiality test. 1.528-4 Section 1.528-4 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES (CONTINUED) Homeowners Associations § 1.528-4 Substantiality test. (a) In general. In...

  17. 49 CFR 384.301 - Substantial compliance-general requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... must come into substantial compliance with the requirements of subpart B of this part in effect as of... demonstrable combined effect of its statutes, regulations, administrative procedures and practices... personnel), and enforcement practices. (b)(1) A State must come into substantial compliance with the...

  18. 20 CFR 604.6 - Conformity and substantial compliance.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false Conformity and substantial compliance. 604.6... FOR ELIGIBILITY FOR UNEMPLOYMENT COMPENSATION § 604.6 Conformity and substantial compliance. (a) In... for the administration of its UC program. (b) Resolving Issues of Conformity and...

  19. 19 CFR 134.35 - Articles substantially changed by manufacture.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 1 2012-04-01 2012-04-01 false Articles substantially changed by manufacture. 134...; DEPARTMENT OF THE TREASURY COUNTRY OF ORIGIN MARKING Exceptions to Marking Requirements § 134.35 Articles substantially changed by manufacture. (a) Articles other than goods of a NAFTA country. An article used in the...

  20. 26 CFR 1.507-6 - Substantial contributor defined.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 7 2014-04-01 2013-04-01 true Substantial contributor defined. 1.507-6 Section... (CONTINUED) INCOME TAXES (CONTINUED) Private Foundations § 1.507-6 Substantial contributor defined. (a...) Special rules—(1) Contributions defined. The term contribution shall, for purposes of section 507(d)(2...

  1. 20 CFR 416.910 - Meaning of substantial gainful activity.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ....910 Section 416.910 Employees' Benefits SOCIAL SECURITY ADMINISTRATION SUPPLEMENTAL SECURITY INCOME FOR THE AGED, BLIND, AND DISABLED Determining Disability and Blindness Definition of Disability § 416.910 Meaning of substantial gainful activity. Substantial gainful activity means work that—...

  2. 5 CFR 550.183 - Substantial hours requirement.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 1 2014-01-01 2014-01-01 false Substantial hours requirement. 550.183 Section 550.183 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PAY ADMINISTRATION (GENERAL) Premium Pay Law Enforcement Availability Pay § 550.183 Substantial hours requirement....

  3. 5 CFR 550.183 - Substantial hours requirement.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 1 2013-01-01 2013-01-01 false Substantial hours requirement. 550.183 Section 550.183 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PAY ADMINISTRATION (GENERAL) Premium Pay Law Enforcement Availability Pay § 550.183 Substantial hours requirement....

  4. 5 CFR 550.183 - Substantial hours requirement.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 5 Administrative Personnel 1 2012-01-01 2012-01-01 false Substantial hours requirement. 550.183 Section 550.183 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PAY ADMINISTRATION (GENERAL) Premium Pay Law Enforcement Availability Pay § 550.183 Substantial hours requirement....

  5. 5 CFR 550.183 - Substantial hours requirement.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Substantial hours requirement. 550.183 Section 550.183 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PAY ADMINISTRATION (GENERAL) Premium Pay Law Enforcement Availability Pay § 550.183 Substantial hours requirement....

  6. 5 CFR 550.183 - Substantial hours requirement.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 1 2011-01-01 2011-01-01 false Substantial hours requirement. 550.183 Section 550.183 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PAY ADMINISTRATION (GENERAL) Premium Pay Law Enforcement Availability Pay § 550.183 Substantial hours requirement....

  7. Complete oxidation of ethylene over supported gold nanoparticle catalysts.

    PubMed

    Ahn, Ho-Geun; Choi, Byoung-Min; Lee, Do-Jin

    2006-11-01

    Complete oxidation of ethylene was performed over supported noble metals or transition metals oxide catalysts and on monoliths under atmospheric pressure. Gold nanoparticles on Al2O3 or MxOy(M = Mo, Fe, Mn) were prepared by impregnation, coprecipitation, deposition, and dispersion methods. Nanoparticles prepared by impregnation method were irregular and very large above 25 nm, but those by coprecipitation and deposition method were uniformly nanosized at 4-5 nm. The gold nanoparticle were outstandingly active in catalyzing oxidation of ethylene. The activity order of these catalysts with preparation methods was deposition > coprecipitation > impregnation, and Au/Co3O4 prepared by deposition method showed the best performance in ethylene oxidation. The addition of gold particles to MxOy/Al2O3 catalyst enhanced the ethylene oxidation activity significantly. The main role of the gold nanoparticles apparently was to promote dissociative adsorption of oxygen and to enhance the reoxidation of the catalyst.

  8. Enhanced mercury oxidation

    SciTech Connect

    Gretta, W.J.; Wu, S.; Kikkawa, H.

    2009-06-15

    A new catalyst offers a new way to enhance mercury control from bituminous coal-fired power plants. Hitachi has developed an SCR catalyst which satisfies high Hg{sup 0} oxidation and low SO{sub 2} oxidation requirements under high temperatures (716 to 770 F). This triple action catalysts, TRAC can significantly enhance mercury oxidation and reduce or eliminate the need for additional mercury control measures such as activated carbon injection. After laboratory testing, pilot-scale tests confirmed an activity of 1.4-1.7 times higher than that of conventional SCR catalyst. The new catalyst has been successfully applied in a commercial PRB-fired boiler without the need for halogens to be added to the fuel feed or flue gas. 2 figs.

  9. Catalyst reforming process

    SciTech Connect

    Swan, G.A. III

    1989-05-23

    This patent describes a process for catalytically reforming a gasoline boiling range naphtha, with hydrogen, in a semi-regenerative or semi-cyclic reforming process unit comprised of serially connected reactors, inclusive of a lead reactor and one or more downstream reactors, the last of which is the tail reactor, each of which contains a halogenated reforming catalyst comprised of a halide, a Group VIII noble metal, and an inorganic oxide support, the improvement which comprises continuously injecting into each downstream reactor a mixture of water and halide at a water to halide ratio from about 20:1 to about 60:1 wherein the specific ratio of water to halide for each individual downstream reactor is chosen so as to maintain the level of halide on catalyst in each downstream reactor from about 0.5 to 1.5 wt. % based on the total weight of the catalyst.

  10. Oxide Nanocrystal Model Catalysts.

    PubMed

    Huang, Weixin

    2016-03-15

    Model catalysts with uniform and well-defined surface structures have been extensively employed to explore structure-property relationships of powder catalysts. Traditional oxide model catalysts are based on oxide single crystals and single crystal thin films, and the surface chemistry and catalysis are studied under ultrahigh-vacuum conditions. However, the acquired fundamental understandings often suffer from the "materials gap" and "pressure gap" when they are extended to the real world of powder catalysts working at atmospheric or higher pressures. Recent advances in colloidal synthesis have realized controlled synthesis of catalytic oxide nanocrystals with uniform and well-defined morphologies. These oxide nanocrystals consist of a novel type of oxide model catalyst whose surface chemistry and catalysis can be studied under the same conditions as working oxide catalysts. In this Account, the emerging concept of oxide nanocrystal model catalysts is demonstrated using our investigations of surface chemistry and catalysis of uniform and well-defined cuprous oxide nanocrystals and ceria nanocrystals. Cu2O cubes enclosed with the {100} crystal planes, Cu2O octahedra enclosed with the {111} crystal planes, and Cu2O rhombic dodecahedra enclosed with the {110} crystal planes exhibit distinct morphology-dependent surface reactivities and catalytic properties that can be well correlated with the surface compositions and structures of exposed crystal planes. Among these types of Cu2O nanocrystals, the octahedra are most reactive and catalytically active due to the presence of coordination-unsaturated (1-fold-coordinated) Cu on the exposed {111} crystal planes. The crystal-plane-controlled surface restructuring and catalytic activity of Cu2O nanocrystals were observed in CO oxidation with excess oxygen. In the propylene oxidation reaction with O2, 1-fold-coordinated Cu on Cu2O(111), 3-fold-coordinated O on Cu2O(110), and 2-fold-coordinated O on Cu2O(100) were identified

  11. Partial oxidation catalyst

    DOEpatents

    Krumpelt, Michael; Ahmed, Shabbir; Kumar, Romesh; Doshi, Rajiv

    2000-01-01

    A two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion. The dehydrogenation portion is a group VIII metal and the oxide-ion conducting portion is selected from a ceramic oxide crystallizing in the fluorite or perovskite structure. There is also disclosed a method of forming a hydrogen rich gas from a source of hydrocarbon fuel in which the hydrocarbon fuel contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion at a temperature not less than about 400.degree. C. for a time sufficient to generate the hydrogen rich gas while maintaining CO content less than about 5 volume percent. There is also disclosed a method of forming partially oxidized hydrocarbons from ethanes in which ethane gas contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion for a time and at a temperature sufficient to form an oxide.

  12. Catalyst, method of making, and reactions using the catalyst

    DOEpatents

    Tonkovich, Anna Lee Y [Pasco, WA; Wang, Yong [Richland, WA; Gao, Yufei [Kennewick, WA

    2009-03-03

    The present invention includes a catalyst having a layered structure with, (1) a porous support, (2) a buffer layer, (3) an interfacial layer, and optionally (4) a catalyst layer. The invention also provides a process in which a reactant is converted to a product by passing through a reaction chamber containing the catalyst.

  13. Catalyst, Method Of Making, And Reactions Using The Catalyst

    DOEpatents

    Tonkovich, Anna Lee Y.; Wang, Yong; Gao, Yufei

    2004-07-13

    The present invention includes a catalyst having a layered structure with, (1) a porous support, (2) a buffer layer, (3) an interfacial layer, and optionally (4) a catalyst layer. The invention also provides a process in which a reactant is converted to a product by passing through a reaction chamber containing the catalyst.

  14. Catalyst, method of making, and reactions using the catalyst

    DOEpatents

    Tonkovich, Anna Lee Y [Pasco, WA; Wang, Yong [Richland, WA; Gao, Yufei [Kennewick, WA

    2002-08-27

    The present invention includes a catalyst having a layered structure with, (1) a porous support, (2) a buffer layer, (3) an interfacial layer, and optionally (4) a catalyst layer. The invention also provides a process in which a reactant is converted to a product by passing through a reaction chamber containing the catalyst.

  15. DEVELOPMENT OF PRECIPITATED IRON FISCHER-TROPSCH CATALYSTS

    SciTech Connect

    Dr. Dragomir B. Bukur; Dr. X. Lang; Dr. S. Chokkaram; Dr. L. Nowicki; G. Wei; Dr. Y. Ding; Dr. B. Reddy; Dr. S. Xiao

    1999-07-22

    Despite the current worldwide oil glut, the US will ultimately require large-scale production of liquid (transportation) fuels from coal. Slurry phase Fischer-Tropsch (F-T) technology, with its versatile product slate, may be expected to play a major role in production of transportation fuels via indirect coal liquefaction. Some of the F-T catalysts synthesized and tested at Texas A and M University under DOE Contract No. DE-AC22-89PC89868 were more active than any other known catalysts developed for maximizing production of high molecular weight hydrocarbons (waxes). The objectives of the present contract were to demonstrate repeatability of catalyst performance and reproducibility of preparation procedures of two of these catalysts on a laboratory scale. Improvements in the catalyst performance were attempted through the use of: (a) higher reaction pressure and gas space velocity to maximize the reactor productivity; (b) modifications in catalyst preparation steps; and (c) different pretreatment procedures. Repeatability of catalyst performance and reproducibility of catalyst synthesis procedure have been successfully demonstrated in stirred tank slurry reactor tests. Reactor space-time-yield was increased up to 48% by increasing reaction pressure from 1.48 MPa to 2.17 MPa, while maintaining the gas contact time and synthesis gas conversion at a constant value. Use of calcination temperatures above 300 C, additional CaO promoter, and/or potassium silicate as the source of potassium promoter, instead of potassium bicarbonate, did not result in improved catalyst performance. By using different catalyst activation procedures they were able to increase substantially the catalyst activity, while maintaining low methane and gaseous hydrocarbon selectivities. Catalyst productivity in runs SA-0946 and SA-2186 was 0.71 and 0.86 gHC/g-Fe/h, respectively, and this represents 45-75% improvement in productivity relative to that achieved in Rheinpreussen's demonstration plant

  16. Secret Lives of Catalysts Revealed

    SciTech Connect

    Salmeron, Miquel; Somorjai, Gabor

    2008-01-01

    Miquel Salmeron and Gabor Somorjai of Berkeley Lab's Materials Sciences Division discuss the first-ever glimpse of nanoscale catalysts in action. More information: http://newscenter.lbl.gov/press-releases/2008/10/21/catalysts/

  17. Protein Catalysts by Computational Design

    NASA Astrophysics Data System (ADS)

    Mayo, Stephen

    2001-03-01

    Understanding the relationships between protein sequence, protein structure, and protein function remains as a central challenge in chemistry and biology. Combined computational and experimental approaches aimed at elucidating these relationships have led to a powerful method for the enhancement of naturally occurring proteins and the creation of new protein function. This presentation will briefly cover the development of our computational protein design methodology and will focus primarily on our recent success in designing an enzyme-like protein catalyst that functions as an esterase. The computational protein design methodology that will be described in this presentation promises not only to revolutionize the conduct of biotechnology in the 21st century, but also to provide a tractable approach for studying the relationships between protein fold and the evolvability of protein function.

  18. Improved reformer yield and hydrogen selectivity with tri-metallic catalyst

    SciTech Connect

    Morse, R.W.; Vance, P.W.; Novak, W.J.; Franck, J.P.; Plumail, J.C.

    1995-09-01

    A new tri-metallic reforming catalyst has been developed for semi-regenerative reforming. This catalyst gives improved C{sub 5} + yield and improved hydrogen yield compared with conventional Pt/Re catalyst. Its stability is equivalent to balanced Pt/Re catalyst. The catalyst is in use in several commercial units and the commercial data confirms the increase in yield and the stability of the catalyst. The improved yield substantially impacts the refiners economics. The annual increase in product value ranges from 0.6 MM$/year to 2.5 MM$/year for a typical 20,000 BPD reformer at current US product prices, depending on the refinery hydrogen balance.

  19. Regeneration of silica-supported silicotungstic acid as a catalyst for the dehydration of glycerol.

    PubMed

    Katryniok, Benjamin; Paul, Sébastien; Capron, Mickaël; Bellière-Baca, Virginie; Rey, Patrick; Dumeignil, Franck

    2012-07-01

    The dehydration reaction of glycerol to acrolein is catalyzed by acid catalysts. These catalysts tend to suffer from the formation of carbonaceous species on their surface (coking), which leads to substantial degradation of their performances (deactivation). To regenerate the as-deactivated catalysts, various techniques have been proposed so far, such as the co-feeding of oxygen, continuous regeneration by using a moving catalytic bed, or alternating between reaction and regeneration. Herein, we study the regeneration of supported heteropolyacid catalysts. We show that the support has a strong impact on the thermal stability of the active phase. In particular, zirconia has been found to stabilize silicotungstic acid, thus enabling the nondestructive regeneration of the catalyst. Furthermore, the addition of steam to the regeneration feed has a positive impact by hindering the degradation reaction by equilibrium displacement. The catalysts are further used in a periodic reaction/regeneration process, whereby the possibility of maintaining long-term catalytic performances is evidenced.

  20. A new process for catalytic liquefaction of low-rank coal using dispersed MoS{sub 2} catalyst generating in-situ with added H{sub 2}O

    SciTech Connect

    Song, C.S.; Saini, A.K.; Yoneyama, Yoshiharu

    1997-12-31

    It is known that water deactivates hydrogenation catalysts under conventional coal liquefaction conditions, although the beneficial effect of hydrothermal pretreatment has been reported. However, the authors have recently found that using water and a dispersed Mo catalyst precursor together could dramatically improve coal conversion at temperatures (325--375 C) that are much lower than those used in conventional processes (400--470 C). However, adding water to catalytic reactions at 400--450 C decreased coal conversion, although water addition to the noncatalytic runs was slightly beneficial in this high temperature range. In the present work, the authors examined the effect of water in solvent-mediated runs in addition to ``dry`` tests, and explored a temperature-programmed liquefaction procedure to take advantage of the synergetic effect between water and dispersed Mo catalyst precursor at low temperatures for more efficient coal conversion. It was found that reaction using ATTM (ammonium tetrathiomolybdate) with added water at 350 C, followed by water removal and subsequent reaction at 400 C gave good coal conversion and oil yield. To understand the effect of water, model reactions of dinaphthyl ether, abbreviated as DNE, were also carried out using ATTM in the absence and presence of water. Addition of water to ATTM in the model reactions substantially enhanced DNE conversion at 350 C. The combination of 1-step and 2-step model tests revealed that at a low temperature of 350 C, the main role of water is to promote the formation of highly active Mo sulfide catalyst. The liquefaction results coupled with model tests suggest that the presence of water results in substantially higher activity of the in-situ generated MoS{sub 2} catalyst for coal conversion at 350 C. Temperature-programming may be an effective strategy for developing a better liquefaction process using dispersed catalysts. This new process appears to be more effective for conversion of low

  1. Shape-Controlled Metal-Free Catalysts: Facet-Sensitive Catalytic Activity Induced by the Arrangement Pattern of Noncovalent Supramolecular Chains.

    PubMed

    Geng, Guangwei; Chen, Penglei; Guan, Bo; Jiang, Lang; Xu, Zhongfei; Di, Dawei; Tu, Zeyi; Hao, Weichang; Yi, Yuanping; Chen, Chuncheng; Liu, Minghua; Hu, Wenping

    2017-05-23

    Metal-free catalytic materials have recently received broad attention as promising alternatives to metal-involved catalysts. This is owing to their inherent capability to overcome the inevitable limitations of metal-involved catalysts, such as high sensitivity to poisoning, the limited reserves, high cost and scarcity of metals (especially noble metals), etc. However, the lack of shape-controlled metal-free catalysts with well-defined facets is a formidable bottleneck limiting our understandings on the underlying structure-activity relationship at atomic/molecular level, which thereby restrains their rational design. Here, we report that catalytically active crystals of a porphyrin, 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, could be shaped into well-defined cubes and sheet-like tetradecahedrons (TDHD), which are exclusively and predominantly enclosed by {101} and {001} facets, respectively. Fascinatingly, compared to the cubes, the TDHDs display substantially enhanced catalytic activity toward water decontamination under visible-light irradiation, although both the architectures have identical crystalline structure. We disclose that such interesting shape-sensitive catalytic activity is ascribed to the distinct spatial separation efficiency of photogenerated electrons and holes induced by single-channel and multichannel charge transport pathways along noncovalent supramolecular chains, which are arranged as parallel-aligned and 2D network patterns, respectively. Our findings provide an ideal scientific platform to guide the rational design of next-generation metal-free catalysts of desired catalytic performances.

  2. Enhanced Electro-Kinetics of C-C Bond-Splitting during Ethanol Oxidation Reaction using Pt/Rh/Sn Catalyst with a Partially Oxidized Pt and Rh Core and a SnO2 Shell

    DOE PAGES

    Yang, G.; Su, D.; Frenkel, A. I.; ...

    2016-09-04

    Direct ethanol fuel cell (DEFC) is a promising technology for generating electricity via the electro-oxidation of liquid ethanol. Its implementation requires the development of anode catalysts capable of producing CO2 and yielding 12-electron transfer through breaking C-C bond of ethanol. Here we presented comprehensive studies of electro-kinetics of the CO2 generation on Pt/Rh/Sn ternary catalysts. Our studies showed that, for the first time, the tri–phase PtRhOx- SnO2 catalysts with a partially oxidized Pt and Rh core and a SnO2 shell, validated by X-ray absorption analyses and scanning transmission electron microscope-electron energy loss spectroscopy line scan, coincided with a 2.5-fold increasemore » in the CO2 generation rate towards ethanol oxidation reaction, compared with the bi-phase PtRh-SnO2 catalysts with a metallic PtRh alloy core and commercial Pt. These studies provided insight on the design of a new genre of electro-catalysts with a partially oxidized noble metal.« less

  3. Enhanced Electro-Kinetics of C-C Bond-Splitting during Ethanol Oxidation Reaction using Pt/Rh/Sn Catalyst with a Partially Oxidized Pt and Rh Core and a SnO2 Shell

    SciTech Connect

    Yang, G.; Su, D.; Frenkel, A. I.; Teng, X.

    2016-09-04

    Direct ethanol fuel cell (DEFC) is a promising technology for generating electricity via the electro-oxidation of liquid ethanol. Its implementation requires the development of anode catalysts capable of producing CO2 and yielding 12-electron transfer through breaking C-C bond of ethanol. Here we presented comprehensive studies of electro-kinetics of the CO2 generation on Pt/Rh/Sn ternary catalysts. Our studies showed that, for the first time, the tri–phase PtRhOx- SnO2 catalysts with a partially oxidized Pt and Rh core and a SnO2 shell, validated by X-ray absorption analyses and scanning transmission electron microscope-electron energy loss spectroscopy line scan, coincided with a 2.5-fold increase in the CO2 generation rate towards ethanol oxidation reaction, compared with the bi-phase PtRh-SnO2 catalysts with a metallic PtRh alloy core and commercial Pt. These studies provided insight on the design of a new genre of electro-catalysts with a partially oxidized noble metal.

  4. Enhanced Electro-Kinetics of C-C Bond-Splitting during Ethanol Oxidation Reaction using Pt/Rh/Sn Catalyst with a Partially Oxidized Pt and Rh Core and a SnO2 Shell

    SciTech Connect

    Yang, G.; Su, D.; Frenkel, A. I.; Teng, X.

    2016-09-04

    Direct ethanol fuel cell (DEFC) is a promising technology for generating electricity via the electro-oxidation of liquid ethanol. Its implementation requires the development of anode catalysts capable of producing CO2 and yielding 12-electron transfer through breaking C-C bond of ethanol. Here we presented comprehensive studies of electro-kinetics of the CO2 generation on Pt/Rh/Sn ternary catalysts. Our studies showed that, for the first time, the tri–phase PtRhOx- SnO2 catalysts with a partially oxidized Pt and Rh core and a SnO2 shell, validated by X-ray absorption analyses and scanning transmission electron microscope-electron energy loss spectroscopy line scan, coincided with a 2.5-fold increase in the CO2 generation rate towards ethanol oxidation reaction, compared with the bi-phase PtRh-SnO2 catalysts with a metallic PtRh alloy core and commercial Pt. These studies provided insight on the design of a new genre of electro-catalysts with a partially oxidized noble metal.

  5. Iridium-catalyst-based autonomous bubble-propelled graphene micromotors with ultralow catalyst loading.

    PubMed

    Wang, Hong; Sofer, Zdeněk; Eng, Alex Yong Sheng; Pumera, Martin

    2014-11-10

    A novel concept of an iridium-based bubble-propelled Janus-particle-type graphene micromotor with very high surface area and with very low catalyst loading is described. The low loading of Ir catalyst (0.54 at %) allows for fast motion of graphene microparticles with high surface area of 316.2 m(2)  g(-1). The micromotor was prepared with a simple and scalable method by thermal exfoliation of iridium-doped graphite oxide precursor composite in hydrogen atmosphere. Oxygen bubbles generated from the decomposition of hydrogen peroxide at the iridium catalytic sites provide robust propulsion thrust for the graphene micromotor. The high surface area and low iridium catalyst loading of the bubble-propelled graphene motors offer great possibilities for dramatically enhanced cargo delivery. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Metal salt catalysts for enhancing hydrogen spillover

    DOEpatents

    Yang, Ralph T; Wang, Yuhe

    2013-04-23

    A composition for hydrogen storage includes a receptor, a hydrogen dissociating metal doped on the receptor, and a metal salt doped on the receptor. The hydrogen dissociating metal is configured to spill over hydrogen to the receptor, and the metal salt is configured to increase a rate of the spill over of the hydrogen to the receptor.

  7. Multimetallic nanoparticle catalysts with enhanced electrooxidation

    DOEpatents

    Sun, Shouheng; Zhang, Sen; Zhu, Huiyuan; Guo, Shaojun

    2015-07-28

    A new structure-control strategy to optimize nanoparticle catalysis is provided. The presence of Au in FePtAu facilitates FePt structure transformation from chemically disordered face centered cubic (fcc) structure to chemically ordered face centered tetragonal (fct) structure, and further promotes formic acid oxidation reaction (FAOR). The fct-FePtAu nanoparticles show high CO poisoning resistance, achieve mass activity as high as about 2810 mA/mg Pt, and retain greater than 90% activity after a 13 hour stability test.

  8. Reforming with polymetallic catalysts

    SciTech Connect

    Baird, W.C. Jr.

    1988-11-29

    This patent describes a process for catalytically reforming, with hydrogen, a hydrocarbon naphtha feed at reforming conditions, the improvement comprising contacting the naphtha feed, and hydrogen, with a halogenated, supported platinum-rhenium catalyst promoted with iridium agglomerated to exhibit a crystallinity greater than 50 percent, as measured by X-ray.

  9. Zinc sulfide liquefaction catalyst

    DOEpatents

    Garg, Diwakar

    1984-01-01

    A process for the liquefaction of carbonaceous material, such as coal, is set forth wherein coal is liquefied in a catalytic solvent refining reaction wherein an activated zinc sulfide catalyst is utilized which is activated by hydrogenation in a coal derived process solvent in the absence of coal.

  10. Catalyst, 2000-01.

    ERIC Educational Resources Information Center

    Ryan, Barbara E., Ed.

    2001-01-01

    "Catalyst" is a publication designed to assist higher education in developing alcohol and other drug prevention polices and programs that will foster students' academic and social development and promote campus and community safety. Issue 1 of volume 6 introduces a series of "Presidential Profiles" in which university presidents describe their…

  11. Hydrogen evolution reaction catalyst

    DOEpatents

    Subbaraman, Ram; Stamenkovic, Vojislav; Markovic, Nenad; Tripkovic, Dusan

    2016-02-09

    Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

  12. Salesperson, Catalyst, Manager, Leader.

    ERIC Educational Resources Information Center

    Worth, Michael J.; Asp, James W., II

    1996-01-01

    This article examines four roles of the college or university development officer: salesperson (when direct solicitation is seen as the officer's primary role); catalyst (or sales manager, adviser, expert, facilitator); manager (stressing the importance of the overall office functioning); and leader (who exerts a leadership role in the…

  13. Structure and function of real catalysts

    NASA Astrophysics Data System (ADS)

    Klier, K.

    1984-11-01

    such as carbon monoxide or unsaturated hydrocarbons through back-bonding of the copper d-orbitals into the π ∗ orbitals of the substrates. In a paper by D.L. Roberts and G.L. Griffin at this Symposium, additional evidence is presented that the same finely dispersed Cu species are the chemisorption and activation sites for hydrogen. Some significant mechanistic features of carbon monoxide hydrogenation are demonstrated by the enhancement of methanol synthesis rates and carbon-carbon bond formation in the presence of alkali promoters. The nature and concentration of the alkali ions on the catalyst surface determine the outcome of the carbon monoxide hydrogenations in the following way: (i) of all the alkali and alkaline earth promoters, cesium displays the most pronounced effects; (ii) at high temperatures and low hydrogen-to-carbon monoxide ratios, maximum amount of n-propanol and 2-methyl-propanol is observed in the product over the Cs/Cu/ZnO catalysts, consistent with the function of the alkali as base catalysts in aldol condensation of aldehydic or enolic surface intermediates; (iii) at low temperatures and high hydrogen-to-carbon monoxide ratios, cesium enhances methanol synthesis as well as water gas shift rates in water- and CO 2-free synthesis gas, retards the methanol synthesis rate in synthesis gas containing intermediate amounts of water, primarily due to loss of surface area upon cesium doping, and again accelerates the synthesis in water-rich synthesis gas. These latter effects point to a mechanism in which the rate of formation of surface formate is enhanced by cesium in water-free synthesis gas and a rapid removal of surface hydroxyls free sites that activate hydrogen in water-rich synthesis gas. The role of Group VIII metals as promoters of the Cu/ZnO catalysts for low alcohol and hydrocarbon synthesis is represented by the effects of small additions of iron. Product composition is intermediate between that in methanol and Fischer-Tropsch syntheses

  14. SCALEUP OF ALUMINUM PHOSPHATE CATALYST FOR PILOT PLANT LPDMEtm RUN

    SciTech Connect

    Andrew W. Wang

    2002-01-01

    The Liquid Phase Dimethyl Ether (LPDME{trademark}) process converts synthesis gas to dimethyl ether in a single slurry bubble column reactor. A mixed slurry of methanol synthesis catalyst and methanol dehydration catalyst in a neutral mineral oil simultaneously synthesizes methanol from syngas and converts some of it to dimethyl ether and water. The reaction scheme is shown below: 2H{sub 2} + CO = CH{sub 3}OH; 2CH{sub 3}OH = CH{sub 3}OCH{sub 3} + H{sub 2}O; H{sub 2}O + CO = CO{sub 2} + H{sub 2}. Most of the water produced in this reaction is converted to hydrogen by reduction with carbon monoxide (water gas shift reaction). This synergy permits higher per pass conversion than methanol synthesis alone. The enhancement in conversion occurs because dehydration of the methanol circumvents the equilibrium constraint of the syngas-to-methanol step. The slurry bubble column reactor provides the necessary heat transfer capacity to handle the greater heat duty associated with high conversion. In order to improve the stability of the catalyst system, non-stoichiometric aluminum phosphate was proposed as the dehydration catalyst for the LPDME{trademark} process. This aluminum phosphate material is a proprietary catalyst. This catalyst system of a standard methanol catalyst and the aluminum phosphate provided stable process performance that met the program targets under our standard test process conditions in the laboratory. These targets are (1) an initial methanol equivalent productivity of 28 gmol/kg/hr, (2) a CO{sub 2}-free, carbon selectivity of 80% to dimethyl ether and (3) stability of both catalysts equivalent to that of the methanol catalyst in the absence of the aluminum phosphate. A pilot plant trial of the LPDME{trademark} process using the aluminum phosphate catalyst was originally planned for March 1998 at the DOE-owned, Air Products (APCI)-operated facility at LaPorte, Texas. Because the aluminum phosphate catalyst is not commercially available, we initiated a

  15. SCALEUP OF ALUMINUM PHOSPHATE CATALYST FOR PILOT PLANT LPDMEtm RUN

    SciTech Connect

    Andrew W. Wang

    2002-05-15

    The Liquid Phase Dimethyl Ether (LPDME{trademark}) process converts synthesis gas to dimethyl ether in a single slurry bubble column reactor. A mixed slurry of methanol synthesis catalyst and methanol dehydration catalyst in a neutral mineral oil simultaneously synthesizes methanol from syngas and converts some of it to dimethyl ether and water. The reaction scheme is: 2H{sub 2} + CO = CH{sub 3}OH 2CH{sub 3}OH = CH{sub 3}OCH{sub 3} + H{sub 2}O H{sub 2}O + CO = CO{sub 2} + H{sub 2}. Most of the water produced in this reaction is converted to hydrogen by reduction with carbon monoxide (water gas shift reaction). This synergy permits higher per pass conversion than methanol synthesis alone. The enhancement in conversion occurs because dehydration of the methanol circumvents the equilibrium constraint of the syngas-to-methanol step. The slurry bubble column reactor provides the necessary heat transfer capacity to handle the greater heat duty associated with high conversion. In order to improve the stability of the catalyst system, non-stoichiometric aluminum phosphate was proposed as the dehydration catalyst for the LPDME{trademark} process. This aluminum phosphate material is a proprietary catalyst. This catalyst system of a standard methanol catalyst and the aluminum phosphate provided stable process performance that met the program targets under our standard test process conditions in the laboratory. These targets are (1) an initial methanol equivalent productivity of 28 gmol/kg/hr, (2) a CO{sub 2}-free, carbon selectivity of 80% to dimethyl ether and (3) stability of both catalysts equivalent to that of the methanol catalyst in the absence of the aluminum phosphate. A pilot plant trial of the LPDME{trademark} process using the aluminum phosphate catalyst was originally planned for March 1998 at the DOE-owned, Air Products (APCI)-operated facility at LaPorte, Texas. Because the aluminum phosphate catalyst is not commercially available, we initiated a scaleup project

  16. Enhanced conversion of syngas to liquid motor fuels

    DOEpatents

    Coughlin, Peter K.; Rabo, Jule A.

    1986-01-01

    Synthesis gas comprising carbon monoxide and hydrogen is converted to C.sub.5.sup.+ hydrocarbons suitable for use as liquid motor fuels by contact with a dual catalyst system capable of enhancing the selectivity of said conversion to motor fuel range hydrocarbons and the quality of the resulting motor fuel product. The catalyst composition employs a Fischer-Tropsch catalyst, together with a co-catalyst/support component comprising SAPO silicoaluminophosphate, non-zeolitic molecular sieve catalyst.

  17. Alumina-supported Pd-Ag catalysts for low-temperature CO and methanol oxidation

    NASA Technical Reports Server (NTRS)

    Mccabe, R. W.

    1987-01-01

    Pd-Ag bimetallic catalysts, supported on gamma-Al2O3, have been evaluated as exhaust catalysts for methanol-fueled vehicles. Laboratory studies have shown that a 0.01% Pd-5% Ag catalyst has greater CO and CH3OH oxidation activity than either 0.01% Pd or 5% Ag catalysts alone. Moreover, Pd and Ag interact synergistically in the bimetallic catalyst to produce greater CO and CH3OH oxidation rates and lower yields of methanol partial oxidation products than expected from a mixture of the single-component catalysts. The Pd-Ag synergism results from Pd promoting the rate of O2 adsorption and reaction with CO and CH3OH on Ag. Rate enhancement by the bimetallic catalyst is greatest at short reactor residence times where the oxygen adsorption rate limits the overall reaction rate.

  18. 29 CFR 825.218 - Substantial and grievous economic injury.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... account its ability to replace on a temporary basis (or temporarily do without) the employee on FMLA leave... economic injury. (d) FMLA's substantial and grievous economic injury standard is different from and more...

  19. 29 CFR 825.218 - Substantial and grievous economic injury.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... account its ability to replace on a temporary basis (or temporarily do without) the employee on FMLA leave... economic injury. (d) FMLA's substantial and grievous economic injury standard is different from and more...

  20. 29 CFR 825.218 - Substantial and grievous economic injury.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... account its ability to replace on a temporary basis (or temporarily do without) the employee on FMLA leave... economic injury.” (d) FMLA's “substantial and grievous economic injury” standard is different from and more...

  1. Center pivot, showing substantial beams that support the trusses. Looking ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Center pivot, showing substantial beams that support the trusses. Looking north from civilian land. - Naval Supply Annex Stockton, Daggett Road Bridge, Daggett Road traversing Burns Cut Off, Stockton, San Joaquin County, CA

  2. 49 CFR 384.301 - Substantial compliance-general requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Compliance § 384.301 Substantial compliance-general requirements. Link to an amendment published at 75 FR... mechanisms, resource assignments (facilities, equipment, and personnel), and enforcement practices. (b)(1) A...

  3. Hydroprocessing catalyst composition

    SciTech Connect

    Apelian, M.R.; Degnan, T.F. Jr.; Marler, D.O.; Mazzone, D.N.

    1993-07-13

    A bifunctional hydroprocessing catalyst is described which comprises a metal component having hydrogenation/dehydrogenation functionality and a support component comprising an inorganic, non-layered, porous, crystalline phase material having pores with diameters of at least about 13 [angstrom] and exhibiting, after calcination, an X-ray diffraction pattern with at least one peak with a relative intensity of 100 at a d-spacing greater than about 18 [angstrom], the catalyst having a surface area S, where S, expressed in m[sup 2].g[sup [minus]1], is defined by the equation: S[ge]600-13.3X where X is the total metals loading in weight percent and is least 12 weight percent. A second hydroprocessing catalyst is described according to claim 1 in which the crystalline phase has a composition expressed as follows: M[sub n/q](W[sub a]X[sub b]Y[sub c]Z[sub d]O[sub h]) wherein M is one or more ions; n is the charge of the composition excluding M expressed as oxides; q is the weighted molar average valence of M; n/q is the number of moles or mole fraction of M; W is one or more divalent elements; X is one or more trivalent elements; Y is one or more tetravalent elements; Z is one or more pentavalent elements; a, b, c, and d are mole fraction of W, X, Y, and Z, respectively, h is a number of from 1 to 2.5; and (a+b+c+d) = 1. A third hydroprocessing catalyst is described according to claim 1 in which the catalyst is at least one base metal of Group VIA, VIIA or VIIIA of the Periodic Table.

  4. Catalyst support structure, catalyst including the structure, reactor including a catalyst, and methods of forming same

    DOEpatents

    Van Norman, Staci A.; Aston, Victoria J.; Weimer, Alan W.

    2017-05-09

    Structures, catalysts, and reactors suitable for use for a variety of applications, including gas-to-liquid and coal-to-liquid processes and methods of forming the structures, catalysts, and reactors are disclosed. The catalyst material can be deposited onto an inner wall of a microtubular reactor and/or onto porous tungsten support structures using atomic layer deposition techniques.

  5. Molybdenum sulfide/carbide catalysts

    DOEpatents

    Alonso, Gabriel; Chianelli, Russell R.; Fuentes, Sergio; Torres, Brenda

    2007-05-29

    The present invention provides methods of synthesizing molybdenum disulfide (MoS.sub.2) and carbon-containing molybdenum disulfide (MoS.sub.2-xC.sub.x) catalysts that exhibit improved catalytic activity for hydrotreating reactions involving hydrodesulfurization, hydrodenitrogenation, and hydrogenation. The present invention also concerns the resulting catalysts. Furthermore, the invention concerns the promotion of these catalysts with Co, Ni, Fe, and/or Ru sulfides to create catalysts with greater activity, for hydrotreating reactions, than conventional catalysts such as cobalt molybdate on alumina support.

  6. Statistical Optimization for Acid Hydrolysis of Microcrystalline Cellulose and Its Physiochemical Characterization by Using Metal Ion Catalyst

    PubMed Central

    Karim, Md. Ziaul; Chowdhury, Zaira Zaman; Abd Hamid, Sharifah Bee; Ali, Md. Eaqub

    2014-01-01

    Hydrolyzing the amorphous region while keeping the crystalline region unaltered is the key technology for producing nanocellulose. This study investigated if the dissolution properties of the amorphous region of microcrystalline cellulose can be enhanced in the presence of Fe3+ salt in acidic medium. The process parameters, including temperature, time and the concentration of metal chloride catalyst (FeCl3), were optimized by using the response surface methodology (RSM). The experimental observation demonstrated that temperature and time play vital roles in hydrolyzing the amorphous sections of cellulose. This would yield hydrocellulose with higher crystallinity. The factors that were varied for the production of hydrocellulose were the temperature (x1), time (x2) and FeCl3 catalyst concentration (x3). Responses were measured in terms of percentage of crystallinity (y1) and the yield (y2) of the prepared hydrocellulose. Relevant mathematical models were developed. Analysis of variance (ANOVA) was carried out to obtain the most significant factors influencing the responses of the percentage of crystallinity and yield. Under optimum conditions, the percentage of crystallinity and yield were 83.46% and 86.98% respectively, at 90.95 °C, 6 h, with a catalyst concentration of 1 M. The physiochemical characteristics of the prepared hydrocellulose were determined in terms of XRD, SEM, TGA and FTIR analyses. The addition of FeCl3 salt in acid hydrolyzing medium is a novel technique for substantially increasing crystallinity with a significant morphological change. PMID:28788226

  7. Separation of catalyst from Fischer-Tropsch slurry

    DOEpatents

    White, C.M.; Quiring, M.S.; Jensen, K.L.; Hickey, R.F.; Gillham, L.D.

    1998-10-27

    In a catalytic process for converting synthesis gas including hydrogen and carbon monoxide to hydrocarbons and oxygenates by a slurry Fischer-Tropsch synthesis, the wax product along with dispersed catalyst is removed from the slurry and purified by removing substantially all of the catalyst prior to upgrading the wax and returning a portion to the Fischer-Tropsch reaction. Separation of the catalyst particles from the wax product is accomplished by dense gas and/or liquid extraction in which the organic compounds in the wax are dissolved and carried away from the insoluble inorganic catalyst particles that are primarily inorganic in nature. The purified catalyst-free wax product can be subsequently upgraded by various methods such as hydrogenation, isomerization, hydrocracking, conversion to gasoline and other products over ZSM-5 aluminosilicate zeolite, etc. The catalyst particles are returned to the Fischer-Tropsch Reactor by mixing them with a wax fraction of appropriate molecular weight, boiling point and viscosity to avoid reactor gelation. 2 figs.

  8. Separation of catalyst from Fischer-Tropsch slurry

    DOEpatents

    White, Curt M.; Quiring, Michael S.; Jensen, Karen L.; Hickey, Richard F.; Gillham, Larry D.

    1998-10-27

    In a catalytic process for converting synthesis gas including hydrogen and carbon monoxide to hydrocarbons and oxygenates by a slurry Fischer-Tropsch synthesis, the wax product along with dispersed catalyst is removed from the slurry and purified by removing substantially all of the catalyst prior to upgrading the wax and returning a portion to the Fischer-Tropsch reaction. Separation of the catalyst particles from the wax product is accomplished by dense gas and/or liquid extraction in which the organic compounds in the wax are dissolved and carried away from the insoluble inorganic catalyst particles that are primarily inorganic in nature. The purified catalyst free wax product can be subsequently upgraded by various methods such as hydrogenation, isomerization, hydrocracking, conversion to gasoline and other products over ZSM-5 aluminosilicate zeolite, etc. The catalyst particles are returned to the Fischer-Tropsch Reactor by slurring them with a wax fraction of appropriate molecular weight, boiling point and viscosity to avoid reactor gelation.

  9. Novel bimetallic dispersed catalysts for temperature-programmed coal liquefaction

    SciTech Connect

    Chunshan, Song; Kirby, S.; Schmidt, E.

    1995-12-31

    The objective of this project is to explore bimetallic dispersed catalysts for more efficient coal liquefaction. Coal liquefaction involves cleavage of methylene, dimethylene and ether bridges connecting various aromatic units and the reactions of various oxygen functional groups. This paper describes recent results on (1) hydrodeoxygenation of O-containing polycyclic model compounds using novel organometallic catalyst precursors; and (2) activity and selectivity of dispersed Fe catalysts from organometallic and inorganic precursors for hydrocracking of 4-(1-naphthylmethyl) bibenzyl. The results showed that some iron containing catalysts have higher activity in the sulfur-free form, contrary to conventional wisdom. Adding sulfur to Fe precursors with Cp-ligands decreased the activity of the resulting catalyst. This is in distinct contrast to the cases with iron pentacarbonyl and superfine Fe{sub 2}O{sub 3}, where S addition increased their catalytic activity substantially. A positive correlation between sulfur addition and increased activity can be seen, but a reversed trend between Fe cluster size and hydrocracking conversion could be observed, for carbonyl-type Fe precursors. It is apparent that the activity and selectivity of Fe catalysts for NMBB conversion depends strongly on both the type of ligand environment, the oxidation state and the number of intermetal bonds in the molecular precursor.

  10. Preparation of arrays of long carbon nanotubes using catalyst structure

    SciTech Connect

    Zhu, Yuntian T.; Arendt, Paul; Li, Qingwen; Zhang, Xiefie

    2016-03-22

    A structure for preparing an substantially aligned array of carbon nanotubes include a substrate having a first side and a second side, a buffer layer on the first side of the substrate, a catalyst on the buffer layer, and a plurality of channels through the structure for allowing a gaseous carbon source to enter the substrate at the second side and flow through the structure to the catalyst. After preparing the array, a fiber of carbon nanotubes may be spun from the array. Prior to spinning, the array can be immersed in a polymer solution. After spinning, the polymer can be cured.

  11. Strontium cobaltite oxygen sponge catalyst and methods of use

    DOEpatents

    Lee, Ho Nyung; Jeen, Hyoungjeen; Choi, Woo Seok; Biegalski, Michael; Folkman, Chad M.; Tung, I-Cheng; Fong, Dillon D.; Freeland, John W.; Shin, Dongwon; Ohta, Hiromichi; Chisholm, Matthew F.

    2017-01-24

    Rapid, reversible redox activity may be accomplished at significantly reduced temperatures, as low as about 200.degree. C., from epitaxially stabilized, oxygen vacancy ordered SrCoO.sub.2.5 and thermodynamically unfavorable perovskite SrCoO.sub.3-.delta.. The fast, low temperature redox activity in SrCoO.sub.3-.delta. may be attributed to a small Gibbs free energy difference between the two topotactic phases. Epitaxially stabilized thin films of strontium cobaltite provide a catalyst adapted to rapidly transition between oxidation states at substantially low temperatures. Methods of transitioning a strontium cobaltite catalyst from a first oxidation state to a second oxidation state are described.

  12. KF-loaded mesoporous Mg-Fe bi-metal oxides: high performance transesterification catalysts for biodiesel production.

    PubMed

    Tao, Guiju; Hua, Zile; Gao, Zhe; Zhu, Yan; Zhu, Yan; Chen, Yu; Shu, Zhu; Zhang, Lingxia; Shi, Jianlin

    2013-09-21

    Using newly developed mesoporous Mg-Fe bi-metal oxides as supports, a novel kind of high performance transesterification catalysts for biodiesel production has been synthesized. More importantly, the impregnation solvent was for the first time found to substantially affect the structures and catalytic performances of the resultant transesterification catalysts.

  13. Metal-support effects on acetone hydrogenation over platinum catalysts

    SciTech Connect

    Sen, B.; Vannice, M.A. )

    1988-09-01

    Acetone hydrogenation was studied over Pt/TiO{sub 2}, Pt/{eta}-Al{sub 2}O{sub 3}, Pt/SiO{sub 2}, Pt powder, and Pt/Au catalysts to test the hypothesis that the metal-support effect responsible for higher CO hydrogenation rates over certain metal/TiO{sub 2} catalysts represents a phenomenon capable of activating carbonyl bonds in general. Compared with the other catalysts, the high-temperature reduced (HTR) Pt/TiO{sub 2} samples had turnover frequencies more than 500 times higher than those of unsupported Pt and Pt/SiO{sub 2} catalysts, and the specific activity (per g Pt) of the Pt/TiO{sub 2} catalyst was 10 times that of a Pt/SiO{sub 2} catalyst with comparable dispersion. Complete hydrogenation to C{sub 3}H{sub 8} and H{sub 2}O occurred only on large, unsupported Pt crystallites; however, partial hydrogenation to isopropyl alcohol appeared to be structure insensitive and activation energies were similar over all catalysts, as were pressure dependencies, which associates the higher activity with a larger preexponential factor. Only one Langmuir-Hinshelwood model provided a rate expression consistent with experimental results - that which assumed competitive adsorption of H{sub 2} and acetone on the same sites and addition of the second H atom as the rate-determining step. This model is consistent with previous TPD, IR, and EELs studies and is also substantiated by theoretical calculations based on the bond-order conservation method. The much higher activities over Pt/TiO{sub 2} catalysts are attributed to an increase in the active site concentration in the Pt-titania interface region. These special sites are presumed to be defects on the titania surface near the Pt that can activate the carbonyl bond in the presence of atomic hydrogen provided by the Pt. 131 refs.

  14. New catalysts for coal processing: Metal carbides and nitrides

    SciTech Connect

    S. Ted Oyama; David F. Cox

    1999-12-03

    The subject of this research project was to investigate the catalytic properties of a new class of materials, transition metal carbides and nitrides, for treatment of coal liquid and petroleum feedstocks. The main objectives were: (1) preparation of catalysts in unsupported and supported form; (2) characterization of the materials; (3) evaluation of their catalytic properties in HDS and HDN; (4) measurement of the surface properties; and (5) observation of adsorbed species. All of the objectives were substantially carried out and the results will be described in detail below. The catalysts were transition metal carbides and nitrides spanning Groups 4--6 in the Periodic Table. They were chosen for study because initial work had shown they were promising materials for hydrotreating. The basic strategy was first to prepare the materials in unsupported form to identify the most promising catalyst, and then to synthesize a supported form of the material. Already work had been carried out on the synthesis of the Group VI compounds Mo{sub 2}C, Mo{sub 2}N, and WC, and new methods were developed for the Group V compounds VC and NbC. All the catalysts were then evaluated in a hydrotreating test at realistic conditions. It was found that the most active catalyst was Mo{sub 2}C, and further investigations of the material were carried out in supported form. A new technique was employed for the study of the bulk and surface properties of the catalysts, near edge x-ray absorption spectroscopy (NEXAFS), that fingerprinted the electronic structure of the materials. Finally, two new research direction were explored. Bimetallic alloys formed between two transition metals were prepared, resulting in catalysts having even higher activity than Mo{sub 2}C. The performance of the catalysts in hydrodechloration was also investigated.

  15. Nano Catalysts for Diesel Engine Emission Remediation

    SciTech Connect

    Narula, Chaitanya Kumar; Yang, Xiaofan; Debusk, Melanie Moses; Mullins, David R; Mahurin, Shannon Mark; Wu, Zili

    2012-06-01

    The objective of this project was to develop durable zeolite nanocatalysts with broader operating temperature windows to treat diesel engine emissions to enable diesel engine based equipment and vehicles to meet future regulatory requirements. A second objective was to improve hydrothermal durability of zeolite catalysts to at least 675 C. The results presented in this report show that we have successfully achieved both objectives. Since it is accepted that the first step in NO{sub x} conversion under SCR (selective catalytic reduction) conditions involves NO oxidation to NO{sub 2}, we reasoned that catalyst modification that can enhance NO oxidation at low-temperatures should facilitate NO{sub x} reduction at low temperatures. Considering that Cu-ZSM-5 is a more efficient catalyst than Fe-ZSM-5 at low-temperature, we chose to modify Cu-ZSM-5. It is important to point out that the poor low-temperature efficiency of Fe-ZSM-5 has been shown to be due to selective absorption of NH{sub 3} at low-temperatures rather than poor NO oxidation activity. In view of this, we also reasoned that an increased electron density on copper in Cu-ZSM-5 would inhibit any bonding with NH{sub 3} at low-temperatures. In addition to modified Cu-ZSM-5, we synthesized a series of new heterobimetallic zeolites, by incorporating a secondary metal cation M (Sc{sup 3+}, Fe{sup 3+}, In{sup 3+}, and La{sup 3+}) in Cu exchanged ZSM-5, zeolite-beta, and SSZ-13 zeolites under carefully controlled experimental conditions. Characterization by diffuse-reflectance ultra-violet-visible spectroscopy (UV-Vis), X-ray powder diffraction (XRD), extended X-ray absorption fine structure spectroscopy (EXAFS) and electron paramagnetic resonance spectroscopy (EPR) does not permit conclusive structural determination but supports the proposal that M{sup 3+} has been incorporated in the vicinity of Cu(II). The protocols for degreening catalysts, testing under various operating conditions, and accelerated aging

  16. A facile strategy to synthesize three-dimensional Pd@Pt core-shell nanoflowers supported on graphene nanosheets as enhanced nanoelectrocatalysts for methanol oxidation.

    PubMed

    Chen, Yi; Yang, Jia; Yang, Ying; Peng, Zhiyao; Li, Jinhua; Mei, Tao; Wang, Jianying; Hao, Ming; Chen, Yalin; Xiong, Weilai; Zhang, Liu; Wang, Xianbao

    2015-07-04

    Here we demonstrate for the first time a water-based surfactant-free synthesis of three-dimensional porous Pd@Pt core-shell nanoflowers on graphene. The obtained Pd@Pt-graphene hybrids exhibited substantially enhanced electrocatalytic activity and stability relative to the commercial Pt/C catalyst originating from this exquisite nanoarchitecture for three-dimensional molecular accessibility and graphene-metal interaction.

  17. Intermediate Ethanol Blends Catalyst Durability Program

    SciTech Connect

    West, Brian H; Sluder, Scott; Knoll, Keith; Orban, John; Feng, Jingyu

    2012-02-01

    In the summer of 2007, the U.S. Department of Energy (DOE) initiated a test program to evaluate the potential impacts of intermediate ethanol blends (also known as mid-level blends) on legacy vehicles and other engines. The purpose of the test program was to develop information important to assessing the viability of using intermediate blends as a contributor to meeting national goals for the use of renewable fuels. Through a wide range of experimental activities, DOE is evaluating the effects of E15 and E20 - gasoline blended with 15% and 20% ethanol - on tailpipe and evaporative emissions, catalyst and engine durability, vehicle driveability, engine operability, and vehicle and engine materials. This report provides the results of the catalyst durability study, a substantial part of the overall test program. Results from additional projects will be reported separately. The principal purpose of the catalyst durability study was to investigate the effects of adding up to 20% ethanol to gasoline on the durability of catalysts and other aspects of the emissions control systems of vehicles. Section 1 provides further information about the purpose and context of the study. Section 2 describes the experimental approach for the test program, including vehicle selection, aging and emissions test cycle, fuel selection, and data handling and analysis. Section 3 summarizes the effects of the ethanol blends on emissions and fuel economy of the test vehicles. Section 4 summarizes notable unscheduled maintenance and testing issues experienced during the program. The appendixes provide additional detail about the statistical models used in the analysis, detailed statistical analyses, and detailed vehicle specifications.

  18. Application of sodium carbonate prevents sulphur poisoning of catalysts in automated total mercury analysis

    NASA Astrophysics Data System (ADS)

    McLagan, David S.; Huang, Haiyong; Lei, Ying D.; Wania, Frank; Mitchell, Carl P. J.

    2017-07-01

    Analysis of high sulphur-containing samples for total mercury content using automated thermal decomposition, amalgamation, and atomic absorption spectroscopy instruments (USEPA Method 7473) leads to rapid and costly SO2 poisoning of catalysts. In an effort to overcome this issue, we tested whether the addition of powdered sodium carbonate (Na2CO3) to the catalyst and/or directly on top of sample material increases throughput of sulphur-impregnated (8-15 wt%) activated carbon samples per catalyst tube. Adding 5 g of Na2CO3 to the catalyst alone only marginally increases the functional lifetime of the catalyst (31 ± 4 g of activated carbon analyzed per catalyst tube) in relation to unaltered catalyst of the AMA254 total mercury analyzer (17 ± 4 g of activated carbon). Adding ≈ 0.2 g of Na2CO3 to samples substantially increases (81 ± 17 g of activated carbon) catalyst life over the unaltered catalyst. The greatest improvement is achieved by adding Na2CO3 to both catalyst and samples (200 ± 70 g of activated carbon), which significantly increases catalyst performance over all other treatments and enables an order of magnitude greater sample throughput than the unaltered samples and catalyst. It is likely that Na2CO3 efficiently sequesters SO2, even at high furnace temperatures to produce Na2SO4 and CO2, largely negating the poisonous impact of SO2 on the catalyst material. Increased corrosion of nickel sampling boats resulting from this methodological variation is easily resolved by substituting quartz boats. Overall, this variation enables an efficient and significantly more affordable means of employing automated atomic absorption spectrometry instruments for total mercury analysis of high-sulphur matrices.

  19. Carbon nanotube patterning with capillary micromolding of catalyst.

    PubMed

    Lee, Jaewon; Ryu, Choonghan; Lee, Sungwoo; Jung, Donggeun; Kim, Hyoungsub; Chae, Heeyeop

    2007-11-01

    Patterning of multi-walled carbon nanotube (MWNT) in a plasma enhanced chemical vapor deposition (PECVD) chamber has been achieved by catalyst patterning using capillary micromolding process. Iron acetate catalyst nanoparticles were dissolved in ethanol and mold was fabricated with polydimethylsiloxane (PDMS). The ethanol solution containing catalyst nanoparticles was filled into the microchannel formed between PDMS mold and Si-wafer by capillary force. The capillary action of different solvents was simulated by commercial CFD-ACE+ simulation code to determine optimal solvents. Simulated result shows that the choice of solvent was critical in this capillary filling process. After the catalyst patterning, MWNT was grown at 700 approximately 800 degrees C by PECVD process using CH4 and Ar gas in a scale of approximately 10 micro-meters in a tubular inductively coupled plasma reactor. Grown CNTs were analyzed by FE-SEM and Raman Spectroscopy.

  20. Two new cracking catalysts are developed for TCC process

    SciTech Connect

    Anderson, C.D.; Breckenridge, L.L.; Bundens, R.G.; Dwyer, F.G.; Herbst, J.A.

    1987-06-01

    Two new catalysts, Durabead 12 and Durabead 14, have been developed during 1986 for Mobil's Thermofor Catalytic Cracking (TCC) units. Durabead 12 produces significantly more gasoline and distillate at the expense of coke and C/sub 4//sup -/ gas and shows good hydrothermal stability. Durabead 12 has the same low attrition and high density and diffusivity as previous Durabead catalysts (Table 1). As a result, unit retention, regenerability, and flow and pressure drop characteristics of Durabead 12 are excellent. Durabead 14 is a combination of Mobil's ZSM-5 shape-selective zeolite and Durabead 12. Durabead 14 has very favorable coke selectivity, octane, and potential alkylate enhancement with no gasoline yield loss compared to conventional rare earth Y (REY) cracking catalysts. Results of laboratory tests on both catalysts are presented in this article. Additional commercial evaluation of Durabead 12 were conducted. Those results are also presented.